THE  LIBRARY 
OF 

THE  UNIVERSITY 

OF  CALIFORNIA 

LOS  ANGELES 


MICROSCOPY  FOR  BEGINNERS 

OR 

COMMON  OBJECTS 
FROM  THE  PONDS  AND  DITCHES 


BY  ALFRED  C.  STOKES,  M.D. 


ILLUSTRATED 


"Tlte  microscope  is  not  the  mere  extension  of  a  faculty  ;  it 
is  a  new  sense" 


"  The  microscope,  frequently  and  intelligently  used,  makes 
nature  pellucid" 


NEW    YORK 
HARPER  &   BROTHERS,  FRANKLIN  SQUARE 

1887 


Copyright,  1887,  by  HARPER  &  BROTHERS. 

All  nglitt  retmed. 


6,2 


CONTENTS. 


FAfll 

INTRODUCTION ix 

CHAPTER  I. 
THE  MICROSCOPE  AKD  ITS  PAKTS 1 

CHAPTER  II. 
COMMON  AQUATIC  PLANTS  USEFUL  TO  THE  MICROSCOPIST 47 

CHAPTER  III. 
DESMIDS,  DIATOMS,  AND  FRESH- AY ATER  ALGJE 64 

CHAPTER  IV. 
RHIZOPODS Ill 

CHAPTER  V. 
INFUSORIA.  . . 


CHAPTER  VI. 
HYDRAS..  .  . .  155 


CHAPTER  VII. 

SOME    AQUATIC    WORMS,   CH^TONOTUS,  AND    CHIRONOMUS 
LARVA...  ..  163 


iv  CONTENTS. 

CHAPTER  VIII.  PAGB 

ROTIFERS 200 

CHAPTER  IX. 

FRESH- WATER  POLYZOA 221 

CHAPTER  X. 
ENTOMOSTRACA  AND  PHYLLOPODA 238 

CHAPTER  XI. 

WATER-MITES  AND  THE  WATER-BEAR 260 

CHAPTER  XII. 
SOME  COMMON  OBJECTS  WORTH  EXAMINING 274 

GLOSSARY 293 

INDEX...  ..  299 


ILLUSTRATIONS. 


FIG. 

p 

VGE 

FIG. 

PAGE 

1. 

A  Pocket-lens 

3 

23. 

Closterium  juncidum  

.   78 

2. 

A  Compound  Microscope.  .  . 

9 

24. 

Closterium  acerosum  

.   79 

3. 

A  Growing-slide  

39 

25. 

Closterium  Lunula  

.   79 

4. 

Air-bubbles  

40 

26. 

Closterium  Ehrenbergii  .  .  . 

.  79 

6. 

Reflector    for    Drawing    the 

27. 

Closterium  acuminatum.  .  . 

.   79 

Magnified  Object  

42 

28. 

Closterium  Diana;       .    ... 

79 

6. 

Leaf  of  Ranunculus  anuati- 

29. 

Closterium  "Venus 

79 

lis  

49 

30. 

Closterium  rostratum  

.   80 

7. 

Peduncle  of  Nymphsea  odo- 

31. 

Closterium  setaceum  

.   80 

rata  :  transverse  section.  . 

50 

32. 

Micrasterias  radiosa 

81 

8. 

Whorl      of      Myriophyllum 

33. 

Micrasterias  rotata  

81 

Leaves  

52 

34. 

Micrasterias  truncata  

.   81 

9. 

A  Leaf  of  Utricularia.  .  .  . 

53 

35. 

Micrasterias  arcuata  

82 

10. 

Quadrifid  Process  from  Inner 

36. 

Micrasterias  dichotoma  .  .  . 

.   82 

Surface  of  Utricle  of  Utri- 

37. 

Micrasterias  Kitchelii  

.   82 

cularia  

55 

38. 

Micrasterias  oscitans  

.   82 

11. 

Whorl  of  Leaves  of  Cerato- 

39. 

Micrasterias  laticeps  

.   82 

phyllum  ... 

56 

40. 

Euastrum  crassum 

83 

12. 

Letnna  pol  yrrhiza  

57 

41. 

Euastrum  didelta  

.   83 

13. 

Lemna  Minor  

58 

42. 

Euastrum  ansatum  

.   83 

M, 

Anacharis  Canadensis  

5'J 

43. 

Tetmemorus  granulatus  .  .  . 

.   84 

15. 

Portion  of  Leaf  of  Sphagnum 

01 

44. 

Tetmemorus  Brebissonii  .  . 

.   84 

16. 

Riccia  fluitans 

02 

45 

Docidium  Baculum 

84 

17. 

Didymoprium  Grevillii.  .... 

76 

46. 

Docidium  crenulatum  

.   84 

18. 

Sphserozosma  pulehra  

76 

47. 

Cosmarium  Ralfsii  

.   85 

19. 

Hyalothcca  dissiliens  

76 

•18. 

Cosmarium  pyramidatum.  . 

.   85 

20. 

Bambusina  Brebissonii  .... 

76 

49. 

Cosrnarium  margaritiferum 

.    85 

21. 

Dcsmidium  Swartzii  

77 

50. 

Cosmarium  Brebissonii  .  .  . 

.   85 

22. 

Closterium  liueatum  

78 

51. 

Staurastrum  punctulatum  . 

.   86 

ILLUSTRATIONS. 


FIG. 

PAGE 

86 

FIG. 

PAGE 

107 

86 

88    Vaucheria  

108 

86 

109 

55.  Xanthidium  armatum  .... 
56.  Xanthidium  antilopaeum  .  . 
57.  Arthrodesmus  iacus  
58.  Arthrodesmus  convergens. 
59.  Spirotaenia  condensata  .... 
60.  Triploceras  verticillatum  .  . 

87 
87 
87 
87 
87 
87 

90.  Draparnaldia  glomerata.  . 
91.  Bulbochaete  
92.  Amoeba  proteus  
93.  Vampyrella  lateritia  
94.  Acanthocystis  cliaetophora 
95.  Actinophrys  sol  

110 
110 
118 
118 
120 
1-?1 

61.  Penium  Brebissonii  
62    Meridion  circulare      .... 

88 
94 

96.  Actinosphaerium      Eich- 

m 

63.  Diatoma  vulgare  
64    Bacillaria 

94 
95 

97.  Difflugia  pyriformis  
98    Difflufia  corona 

124 
125 

65  and  65a.  Fragelaria  capucina 
66.  Ilimantidium  pectinale.  .  .  . 

95 
96 

99.  Centropyxis  aculeata  .... 
100    Arcella  vul^aris  

126 
T>7 

67.  Encyonema  paradoxa  
68  and  68a.  Cocconema  lanceo- 
lata 

96 
96 

101.  Arcella  dentata  
102.  Trinema  enchelys  
103    Eu(rlvpha  alveolata 

127 
127 
129 

69.  Gomphoncnm  acuminata  .  . 
70.  Epithemia  turfida  

97 
97 

104.  Cyphoderia  ampulla  
105    Clathrulina  ele^ans 

129 
1BO 

97 

140 

72.  Eunotia  tctraodon  

97 

107.  Carchesium  

141 

73.  Pleurosigma  

98 

108.  Epistylis  

14"! 

74    Surirella  splendida  

98 

109.  Vorticella    

143 

99 

110    Dinobryon 

144 

99 

111    Va"-inicola 

145 

77.  Piunularia  viridis  

99 

112.  Platvcola  

146 

78.  Stauroneis  phoenoccntcron. 

99 

113.  Cothurnia  

146 

79.  Sccnedcsmus  quadricauda. 
80.  Pediastrum  granulatum  .  .  . 
81.  Hydrodictyon  utriculatum  . 

101 
101 
102 

114.  Stentor  potymorphus    .  .  . 
115.  Stentor  Barrett!  
116.  Stentor  igneus  

147 
148 
148 

82.  Batrachospermum    monili- 
forme  

104 

117.  Astasia  
118.  Euglena  

149 
149 

83.  Anabaena  

105 

119.  Chilomonas 

IfiO 

84.  Oscillaria  

105 

120    Phacus  pleuronectes 

150 

85    Spiro°pyra  

106 

121    Phacus  lonf'icaudus 

150 

86    Spiro°yra   in   conjugation 

122    Uvella 

151 

with  spores  .  .  , 

106 

123.  Trachelocerca  .  . 

151 

ILLUSTRATIONS. 


Vll 


FIG. 

124.  Amphileptus            

PAGE 

159 

FIG. 

149.  Steplianops  

PAGE 

9,17 

159 

150.  Pterodina  

918 

126    Euplotes 

153 

151    Dinocharis             

<>18 

127    Stylonycliia 

153 

152    Polyarthra 

218 

128.  Chilodon  

154 

153.  Brachionus  ,  

9,1ft 

129.  Loxodes     . 

154 

154.  Philodina  

990 

130.  Hydras  adherent  to  Lemna 
rootlets  
130«    Hydra  stin0" 

156 
158 

155.  Pectinatella  magnifica  .  .  . 
155a.  Statoblast  of  Pectinatella 
156  .Plumatella 

229 
230 
231 

1306.  Trichodina     pediculus  — 

160 

157.  Paludicella  
158.  Urnatella   

233 
935 

167 

159    Daphnia 

947 

132    Chsetonotus  larus 

168 

160    Bosmina 

249 

133.  An^uillula    

184 

161.  Cypris  

950 

134    Snout  of  a  Pristiua 

180 

162.  Camptocercus  

951 

163    Chj'dorus 

251 

Pristina  

136.  Posterior   extremity  of  a 

189 

164.  Alonopsis  
165.  Diaptomus  

251 
959 

189 

166.  Canthocamptus 

253 

167    Cvclops 

254 

Dcro  

199, 

167a.  Young  Cyclops  

954 

138.  Posterior  extremity  of  fin 

168.  Limnetis  

955 

Aulophoru.s  
139.  Podal  spines  and  bristles 
of  Strephuris  

193 
194 

169.  Artemia  (a  female)  
170.  Branchipus  (a  male)  
171.  A  Water-mite  

256 
258 
960 

140    Nais 

198 

172    Tlic  Water  -bear  (Macro- 

141.  Podal  Spine  of  Nais..    .  . 

100 

biotus)    

268 

142.  Stephanoceros  
143.  Floscularia  ornata  
144.  Actinurus  
145.  Melicerta  ringens  .  .        .. 

209 
210 
211 
<>13 

173.  Coxae  of  Hydrachna  
174.  COXJE  of  Eylais  
175.  Coxae   of  Arrenurus   (fe- 
male) 

269 
270 

270 

146.  Limnias  ceratophylli.  ,  ..  . 
147.  Megalotrocha  

214 

9,15 

176.  Coxae  of  Arrenurus  (male) 
177.  Coxa!  of  Atax.  .  

271 

9,79, 

148.  Rotifer  vulgaris-  

216 

1  78.  Eye-  plate  of  Limnochares. 

273 

INTRODUCTION. 


To  the  beginner  in  the  \\&Q  of  the  microscope,  indeed  to  the 
beginner  in  the  study  of  any  department  of  natural  history,  the 
name  of  the  specimens  found  is  of  the  first  importance.  It  is 
the  key  that  opens  the  door  to  further  knowledge,  and  until  it 
is  obtained  the  beginner  is  helpless;  the  books  are  closed  to 
him,  all  conference  with  others  in  reference  to  the  object  or 
specimen  is  impossible,  and,  in  many,  a  budding  interest  that 
might  otherwise  bloom  and  bear  fruit  is  crushed  and  destroyed. 
The  first  question  asked  is  always,  "  What  is  it?"  and  unless  the 
questioner  has  a  kind  and  experienced  friend  to  whom  he  can 
take  the  specimen,  or  a  book  of  common  objects  from  which 
the  names  of  ordinary  natural  history  materials  can  be  ascer- 
tained, the  question  is  too  often  unanswered,  and  the  beginner 
soon  loses  his  relish  for  the  unknown  in  nature,  because  to  him 
it  always  remains  the  unknowable. 

In  England  innumerable  little  hand-books  in  all  departments 
of  natural  science  are  within  the  reach  of  every  reader,  even 
the  least  wealthy.  They  are  written  in  an  attractive  style,  they 
are  usually  accurate  as  far  as  they  go,  and  they  aim  to  describe 
the  common  objects  to  be  found  in  the  green  lanes  and  the 
woods,  the  waters  of  the  ponds  and  streams,  and  the  shallow 
bays  and  inlets  of  the  sea,  so  that  any  one  with  the  least 
inclination  towards  the  study  of  the  teeming  world  of  an- 
imal and  vegetable  life  can,  at  slight  expenditure  of  time, 
labor,  and  money,  learn  the  names  of  the  commonest  things 
A* 


X  INTRODUCTION. 

i. 

surrounding  him.  Such  books,  if  correct  and  helpful,  arc  wor- 
thy of  all  praise.  That  there  is  a  desire  for  them,  even  in  this 
fair  land  of  ours,  is  evident  by  their  importation,  and  their  ap- 
pearance on  the  counters  of  the  booksellers  and  the  shelves  of 
the  public  libraries.  But  they  are  seldom  adapted  to  our  needs. 
Their  descriptions  are  commonly  too  general  and  diffuse,  their 
writers  pay  more  attention  to  literary  style  than  to  the  im- 
parting of  definite  information,  and  the  text  too  often  bears 
internal  evidence  of  having  been  made  to  suit  certain  pictures 
owned  and  necessary  to  be  utilized  by  the  publisher.  That 
similar  and  better  books  on  the  life  in  American  fields  and 
streams,  and  American  sea-shores,  are  so  few  is  much  to  be  re- 
gretted. There  ought  to  be  small  and  untechnical  hand-books 
adapted  to  "all  capacities,  even  the  meanest,"  as  our  forefa- 
thers used  to  put  it,  and  in  all  departments  of  animal  and  vege- 
table life ;  books  in  which  the  beginner  could  learn  the  names 
of  things.  "  I  do  beseech  you,  what  is  your  name?"  is  the  oft- 
asked  question,  cot  only  by  the  beginner  in  the  use  of  the 
microscope,  but  by  the  more  advanced  student  in  other  depart- 
ments as  well.  Ernerton's  "Life  on  the  Sea- shore,"  and  his 
"  Structure  and  Habits  of  Spiders ;"  Hervcy's  charming  "  Sea- 
mosses,"  Gray's  "  How  Plants  Grow,"  Romyn  Hitchcock's 
"Synopsis  of  the  Fresh-water  Rhizopods,"  Jordan's  "Manual 
of  the  Vertebrates,"  are  delightful  books  that  approach  the 
ideal  nearer  than  any  others  published  in  this  country  ;  indeed, 
there  are  no  others.  There  is  so  much  for  our  learned  scien- 
tists to  do  in  this  comparatively  unexplored  land  of  ours,  that 
they  may  have  no  time  to  stoop  and  lend  a  hand  to  those  who 
would  like  to  enter  a  little  way  into  the  attractive  world  of  sci- 
ence, from  which  faint  but  pleasant  rumors  occasionally  come. 
They  arc  all  courteous  and  communicative  when  personally  ap- 
proached, but  what  boy  or  other  young  person  with  an  inclina- 
tion towards  "bugs  and  things"  would  be  willing,  or,  indeed, 


INTRODUCTION.  xi 

would  know  how  to  seek  aid  from  these  celebrated  men?  And 
if  the  student  is  alone  in  a  country  place  where  Nature  smiles 
her  sweetest,  but  where  there  are  no  libraries  and  no  human 
being  to  consult,  except,  perhaps,  "  the  minister,"  how  then  shall 
he  learn  the  name  of  the  flower,  the  stone,  or  the  bird  that  at- 
tracts his  attention?  "The  minister"  is  usually  poor  authori- 
ty on  such  subjects,  and  the  boy,  after  wondering  and  investi- 
gating in  an  awkward  and  boyish  fashion,  soon  gives  it  up, 
when  he  might  have  become  a  lover  of  nature,  and  perhaps  a 
lover  of  something  even  better  than  nature.  The  "  Agassiz 
Association,"  with  its  clubs  and  chapters  and  auxiliary  natural 
history  societies,  is  doing  much  good  in  awakening  a  desire  in 
its  young  members  to  know  something  of  natural  science,  and 
in  doing  something  to  help  the  young  investigators.  Yet  it 
can  do  but  little.  The  workers  must  depend  upon  themselves, 
and  the  books,  of  which  there  are  so  few  adapted  to  their  needs. 

The  microscope  is  every  day  becoming  a  more  familiar  in- 
strument to  the  young.  There  is  a  growing  interest  among 
the  boys  and  girls,  even  among  those  of  a  larger  growth,  in  the 
little  things  of  the  world,  and  the  number  of  so-called  micro- 
scopists  is  rapidly  increasing.  But  the  possessor  of  an  instru- 
ment looks  at  the  two  or  three  mounted  objects  supplied  by 
the  dealer,  and  then  wonders  if  this  is  all,  and  if  this  is  the 
only  foundation  for  the  charming  stones  he  has  heard  of  the 
charming  things  to  be  seen  with  the  microscope. 

"  Will  you  tell  me  where  I  can  find  a  book  that  will  help  me  to 
know  a  microscopic  plant  from  a  microscopic  animal,  and  teach 
me  how  I  can  best  collect  them?"  is  a  question  that  has  often,  in 
some  shape,  been  asked  the  writer,  and  has  as  often  remained 
unanswered,  for  there  is  no  book  on  common  American  micro- 
scopic objects.  It  is  only  possible  to  direct  the  questioner  to 
the  ditches  and  the  ponds,  and  to  wish  him  a  success  that  is 
almost  hopeless.  In  any  event,  the  beginner  naturally,  and  al- 


xii  INTRODUCTION. 

most  instinctively,  goes  first  to  the  water  for  liis  microscopic 
objects,  probably  because  lie  has  heard  so  much  about  the  "  ani- 
malcules" there.  His  first  examination  bewilders  him.  There 
is  so  much  life  and  motion  and  color,  there  are  so  many  strange 
forms;  but  where  shall  he  turn  for  help? 

Since  our  illustrious  scientists  have  not  offered  to  help  him, 
the  writer,  who  is  only  a  beginner  himself,  and  who  makes  not 
the  slightest  pretensions,  has  sympathized  with  the  inquirers 
whom  he  has  been  compelled  to  turn  away  unsatisfied  when 
they  have  come  for  printed  help  in  their  microscopical  work, 
and  this  little  book  is  the  result.  It  claims  no  literary  merit ; 
it  makes  no  scientific  pretensions.  Its  only  aim  is  to  help  the 
beginner  to  ascertain  the  names  of  some  of  the  common  mi- 
croscopic creatures,  both  animal  and  vegetable,  with  which  the 
fresh  waters  of  the  land  are  filled,  and  it  tries  to  do  so  in 
the  simplest  and  most  direct  way,  leaping  scientific  hedges  and 
trampling  on  scientific  classification  in  a  manner  that  will  dis- 
may the  learned  botanist  and  zoologist.  But  the  botanist  and 
zoologist  have  weighty  books  that  delight  their  souls,  so  why 
should  not  the  beginner  with  a  microscope  have  a  book  to  help 
him  to  the  names  of  the  commonest  aquatic  objects,  and,  it  is 
hoped,  delight  him  by  smoothing  the  path  that  leads  to  them  ? 
The  writer  will  not  be  greatly  troubled  if  the  learned  botanist 
and  zoologist  do  not  like  this  little  book,  provided  the  beginner 
in  the  use  of  the  microscope  approves  it  and  finds  it  helpful. 

It  relates  almost  exclusively  to  aquatic  objects.  One  reason 
for  this,  has  already  been  mentioned.  Another  and  more  po- 
tent one  is,  that  even  the  beginner  knows,  in  a  general  way, 
what  he  is  looking  at  when  he  magnifies  the  common  objects 
of  the  land,  but  the  microscopic  creatures  from  the  water  are 
so  truly  microscopic,  the  observer  must  so  often  go  fishing  on 
faith,  and  only  know  the  contents  of  his  net  by  faith  and  im- 
agination until  he  can  examine  his  collection  drop  by  drop  with 


INTRODUCTION.  xiii 

the  microscope,  that  lie  is  lost  at  the  start  unless  he  has  a  book 
to  help  him,  which  this  one  hopes  to  do.  But  is  it  necessary 
to  say  that  the  following  pages  do  not  contain  notices  of  ev- 
erything to  be  found  in  the  ponds  and  ditches?  The  begin- 
ner will  capture  many  objects  which  he  will  not  find  described 
here.  It  is  not  possible  that  the  matter  should  be  otherwise. 
The  waters  are  crowded  with  life,  and  it  is  only  the  common- 
est objects  and  those  most  frequently  found,  that  a  little  book 
of  this  kind  can  attempt  to  include. 

The  descriptions  of  those  few  have  been  made  as  plain  as 
possible.  The  writer  has  seldom  allowed  himself  to  "fall  into 
poetry,"  although  often  sorely  tempted.  The  keys  or  analyti- 
cal tables  so  freely  scattered  through  the  pages  have  been  pur- 
posely made  as  artificial  as  they  could  be.  They  use  the  most 
conspicuous  external  characters  without  regard  to  scientific 
classification,  and  without  regard  to  any  result  but  one  only—- 
to help  the  beginner  find  the  name,  at  least  the  generic  name, 
of  his  specimen.  If  this  is  accomplished  the  book  will  have 
attained  its  purpose.  The  method  of  using  the  keys  is  ex- 
plained on  page  70. 

Finally,  to  the  beginners  in  the  use  of  the  microscope,  for 
whom  the  book  has  been  prepared,  the  writer  would  say,  as 
has  so  often  been  already  said :  There  is  DO  royal  road.  The 
mother-bird  finds  and  brings  the  food,  but  even  the  youngest 
nestling  opens  its  own  mouth. 


MICROSCOPY  FOR   BEGINNERS. 


CHAPTER  I. 

THE   MICROSCOPE   AND   ITS    PARTS. 

Simple  and  Compound  Microscopes.— Pocket  -lens.  —  "  Craig  Mi- 
croscope."—"  Excelsior  Microscope."  — Watch-maker's  Glass.— 
Coddington  Lens. — How  to  Focus  a  Simple  Lens. — Parts  of  the 
Compound  Microscope.  —  Draw  -  tube.  —  Eye  -  pieces.  —  Society  - 
screw.— French  Triplets.— Objectives.— Selecting  Objectives  for 
the  Beginner.— Coarse  Adjustment.— Focussing.— Fine  Adjust- 
ment.—  The  Stage. —  Diaphragm. —  Mirror  and  Bull's-eye  Cou- 
densing-lens. — Preparing  the  Object. — Thin  Cover-glass. — Cells. 
— Cement.  — Dry  Mounting. — Needles. — Dipping  -  tube. — Bunsen 
Burner. —Evaporation  from  beneath  the  Cover. —Life -slide.— 
Growing  -  cell.  — Air  -  bubbles.  —  Drawing.  —  Camera  Lucida  and 
Glass  Reflector. —  Micrometer. — Measuring  the  Object. — To  as- 
certain the  Magnifying  Power. — Collecting-bottles. — Books  and 
Magazines  for  Reference. 

MICROSCOPES  are  compound  or  simple :  compound 
when  they  consist  of  two  or  more  glasses,  one  or  more 
being  near  the  object  to  be  examined,  and  one  or  more 
near  the  eye  of  the  observer ;  simple  when  they  consist 
of  but  one  double-convex  lens  to  be  held  near  the  ob- 
ject, or  of  two  or  more  lenses  that  can  be  used  singly  or 
all  at  the  same  time.  "When  thus  used  in  combination, 
the  two  or  three  simple  lenses  are  not  only  placed  close 
1 


2  MICROSCOPY  FOR  BEGINNERS. 

to  each  other,  but  close  to  the  object,  the  combination 
acting  as  if  it  were  a  single  lens,  the  magnifying  power 
being  much  greater  than  that  of  but  one  glass,  and  the 
distance  from  the  object  much  shorter  when  in  focus. 
In  the  compound  microscope  the  lenses  near  the  eye 
magnify  the  image  formed  by  the  lower  glasses,  and 
that  image  is  inverted,  the  upper  side  of  the  object  then 
appearing  to  be  the  lower,  the  right-hand  side  the  left, 
and  the  left-hand  the  right.  In  the  simple  microscope, 
however,  the  image  is  not  inverted ;  and  in  those  forms 
where  two  or  three  lenses  are  combined,  the  effect  is  the 
same  as  though  one  glass  of  great  magnifying  power 
were  used.  But  separate  the  lenses  so  that  the  upper 
shall  magnify  the  image  produced  by  the  lower,  and  you 
have  a  simple  form  of  compound  microscope.  In  the 
simple  microscope  we  see  the  object  itself,  in  the  com- 
pound we  see  the  enlarged  image  of  the  object. 

As  a  simple  microscope  does  not  seem  to  invert  and 
reverse  the  object,  and  because  the  distance  between  the 
two  is  long  when  a  low-power  glass  is  in  focus — that  is, 
when  the  glass  is  in  such  a  position  that  the  magnified 
object  looks  clear  and  distinct  to  the  eye — it  is  always 
used  for  the  examination  of  a  flower,  the  surface  of  a 
piece  of  bark,  a  stone,  an  insect,  or  any  other  specimen 
of  considerable  size,  or  one  that  is  visible  to  the  naked 
eye,  more  extended  study  being  reserved  for  the  com- 
pound instrument  at  home.  A  simple  microscope,  a 
"pocket-lens"  as  it  is  often  and  preferably  called  (Fig.  1), 
is  really  indispensable  to  every  one  who  has  a  taste  for 


THE   MICROSCOPE   AND   ITS  PARTS.  3 

nature  studies,  and  a  desire  to  know  somewhat  of  the 
beauties  hidden  from  our  unaided  vision;  for  the  sim- 
plest glass  shows  the  student  unim- 
agined  charms  in  the  petal  of  a  flow- 
er, the  sand  he  walks  on,  and  in  the 
green  scum  that  floats  on  every  sum- 

J  Fig.  1.— A  Pocket-lens. 

mer  pool  and  disgusts  him  until  his 
little  lens  reveals  its  purity  and  grace.  It  is  always  ready 
for  the  examination  of  anything  picked  up  in  the  fields 
or  woods,  it  is  small,  and  it  is  easily  carried  in  the  pocket. 
It  can  be  obtained  in  a  great  variety  of  shapes,  so  far 
as  the  frame  that  holds  the  lens  is  concerned ;  it  can  be 
had  with  but  one  glass,  or  with  two  or  three  of  various 
powers,  to  be  used  alone  or  combined  ;  it  can  be  bought 
with  a  large  lens  of  low  power  in  one  end  of  the  frame, 
and  a  smaller  glass  of  higher  power  in  the  other.  But 
whatever  form  the  beginner  selects,  he  must  remember 
that  the  larger  the  simple  lens  the  lower,  as  a  rule,  will 
be  the  magnifying  power,  and  the  longer  the  working 
distance,  or  the  space  between  the  glass  and  the  object 
when  in  focus ;  and  the  smaller  the  lens  the  more  con- 
vex it  will  be,  the  greater  power  it  will  have,  the  shorter 
the  working  distance,  and  the  less  of  the  object  it  will 
show  at  one  view,  and  consequently  the  more  trouble- 
some it  will  be  to  use.  The  beginner  is  advised  to  pur- 
chase a  good  pocket -lens  with  a  working  distance,  or 
"focal  length"  as  it  is  sometimes  rather  incorrectly 
termed,  of  one  or  one  and  one-half  inches.  This  is  all 
that  is  really  needed  for  the  examination  of  botanical 


4  MICROSCOPY  FOR  BEGINNERS. 

specimens  and  the  thousand  and  one  objects  that  attract 
the  attention  on  every  summer  ramble. 

The  writer  personally  dislikes  the  combination  pock- 
et-lens formed  of  two  or  three  separable  glasses.  If  but 
one  lens  of  the  combination  is  wanted  for  immediate 
use,  the  entire  number  must  be  pushed  out  of  the  thick 
and  awkward  case,  one  must  be  selected  and  separated, 
for  the  perverse  thing  usually  comes  out  of  the  pocket 
upside  down,  and  it  is  of  course  desirable  that  the  high- 
est-power glass  shall  be  next  to  and  nearest  the  object, 
while  those  not  needed  are  turned  to  one  side,  making  a 
series  of  operations  that  take  time,  both  hands,  and  con- 
siderable patience  if  you  are  anxious  to  examine  the 
specimen.  Your  companion  will  have  finished  the  work 
with  the  single  glass,  and  will  be  telling  you  how  the  ob- 
ject looks,  before  your  complicated  affair  is  ready  to  be- 
gin, provided  you  are  not  wise  enough  to  have  avoided 
the  combination  pocket-lens.  And  if  tire  whole  number 
is  used  at  once,  the  working  distance  is  usually  so  short 
that  the  observer's  head  or  hat-brim  shuts  off  most  of  the 
light,  so  that  the  object  can  be  seen  with  difficulty,  and 
a  very  little  of  it  at  that.  To  see  at  one  view  so  small  a 
portion  as  these  high-power  combinations  always  show, 
and  to  be  compelled  to  pass  the  lens  over  so  many  little 
parts  before  an  idea  of  the  whole  surface  can  be  ob- 
tained, is,  to  say  the  least,  not  satisfactory ;  unless  the 
observer  is  familiar  with  the  entire  object,  and  the  rela- 
tion and  arrangement  of  all  the  parts,  a  low-power  pocket- 
lens  is  the  most  useful,  and  the  one  to  be  recommended. 


THE  MICROSCOPE  AND  ITS  PARTS.  5 

The  reader  perceives  that  this  matter  of  short  focus 
is  an  important  one ;  indeed  the  usefulness  of  the  pock- 
et-lens to  a  great  extent  depends  upon  it.  Reject  with- 
out hesitation  the  simple  lens  whose  focus  is  so  short 
that  it  must  be  held  almost  in  contact  with  the  object. 

Not  long  ago  a  rather  expensive  instrument  called  the 
"  Craig  Microscope"  was  extensively  advertised,  and  sold 
as  a  remarkable  thing.  The  lens  was  a  small  globule  of 
glass  fastened  to  a  glass  plate,  to  give  it  a  flat  under-sur- 
face,  and  mounted  in  a  brass  ring,  the  whole  being  sup- 
ported on  an  upright  brass  tube  with  a  plane  mirror  at 
the  lower  end.  It  was  not  a  compound  microscope,  but 
a  simple  lens  with  mirror  attachment.  The  object  to 
be  examined  was  suspended  from  the  flat  surface  of  the 
glass  in  a  drop  of  water,  the  focus  being  so  short  that 
it  was  at  the  front  of  the  lens,  so  that  nothing  could 
be  looked  at  unless  it  was  adherent  to  the  glass.  No 
mounted  object  could  be  satisfactorily  studied ;  to  ex- 
amine the  parts  of  a  flower  was  impossible,  and  even 
when  a  drop  of  water  was  suspended  from  the  lens  its 
contents  were  distorted  almost  beyond  recognition. 

The  "  Excelsior  Microscope  "  makes  no  false  pretences. 
The  instrument  consists  of  a  small  box  which  is  a  recep- 
tacle for  all  the  parts  when  not  in  use,  and  a  support 
when  the  steel  rod  is  elevated  to  receive  the  combina- 
tion pocket-lens  and  the  stage,  on  which  the  object  is  to 
be  placed,  a  small  mirror  in  the  front  of  the  box  re- 
flecting the  light  to  the  object  from  below.  A  great 
fault  is  the  absence  of  weight  in  the  instrument.  At 


6  MICROSCOPY  FOR  BEGINNERS. 

the  least  touch  it  moves,  the  light  reflected  from  the 
mirror  is  lost,  and  the  object  is  consequently  left  in  semi- 
obscurity.  It  is  intended  chiefly  for  the  dissection  of 
flowers,  grasses,  or  large  insects,  and  fairly  answers  the 
purpose  if  the  observer  desires  to  have  both  hands  free, 
and  cares  to  screw  the  box  to  the  table.  But  it  is  no 
better  than  a  good  pocket-lens,  which,  with  very  little 
trouble,  can  be  attached  to  an  upright  rod  and  be  used 
for  dissections ;  in  some  respects  it  is  much  less  valuable. 
The  three  lenses  supplied  can  be  used  as  a  single  one  or 
combined.  The  former  is  good,  the  combination  of  two 
is  not  seriously  objectionable,  but  the  focus  of  the  united 
three  is,  to  the  writer's  eye,  only  five-sixteenths  of  an 
inch,  a  distance,  aside  from  the  small  field  of  view,  that 
effectually  prevents  its  use  as  a  dissecting  microscope. 
"With  the  lowest-power  lens  six  letters  of  the  type  used 
in  this  book  can  be  seen,  the  focal  distance  being  one 
and  one-fourth  inches ;  with  two  lenses  combined,  four 
letters,  with  a  focal  length  of  about  one -quarter  of  an 
inch ;  and  with  the  three  glasses  only  one  letter  is  vis- 
ible, the  focal  distance  being  five-sixteenths  of  an  inch, 
when  tested  by  the  writer. 

A  "  watch-maker's  glass,"  winch  is  sometimes  seen  on 
the  microscopist's  table,  is  a  simple  lens  mounted  in  a 
short  horn  or  rubber  tube,  so  arranged  that  it  can  be 
held  to  the  eye  by  the  contraction  of  the  muscles  of 
the  cheek  and  brow,  while  both  hands  are  used  for 
the  manipulation  of  the  object.  It  can  be  obtained 
of  various  powers  and  focal  lengths,  but  it  is  scarcely 


THE  MICROSCOPE  AND  ITS  PARTS.  7 

desirable.  The  prolonged  contraction  of  the  facial  mus- 
cles necessary  to  keep  it  in  place  is  very  fatiguing,  and 
the  vapor  always  evaporating  from  the  front  of  the 
eye  being  confined  within  the  tube  is  sure  to  condense 
on  the  lens  and  obscure  the  object.  Everything  a  watch- 
maker's glass  will  do,  a  good  pocket-lens  will  accomplish. 

A  "Coddington  lens"  is  admirable  in  many  respects. 
Its  magnifying  power  is  great,  the  image  it  forms  is  ex- 
cellent, the  field  of  view  is  good,  but  the  focus  is  usually 
unpleasantly  short.  This,  aside  from  its  cost,  is  its  only 
objectionable  feature.  It  is  named  after  the  gentleman 
who  first  brought  it  to  the  notice  of  the  opticians,  and 
not,  as  it  should  have  been,  after  Sir  David  Brewster, 
its  inventor.  It  consists  of  a  sphere  of  glass  with  a  deep 
groove  cut  around  its  centre,  and  filled  with  a  black  ce- 
ment, which  acts  as  a  diaphragm  to  cut  off  certain  rays 
of  light  whose  presence  and  action  would  be  undesira- 
ble, as  they  would  interfere  with  the  formation  of  a  clear 
and  sharply  outlined  image. 

The  reader  may  be  surprised  to  learn  that  there  are 
people  who  do  not  know  how  to  focus  a  lens.  I  have 
seen  such  persons  take  the  glass  as  if  they  were  afraid 
of  it.  They  extend  it  towards  the  object  in  a  hesitating 
way,  move  it  about  irregularly  for  a  few  moments,  throw 
back  the  head,  look  cross-eyed,  and  say,  "  Oh  yes  ;  I  see. 
How  beautiful!  And  how  very  queer  it  looks!"  I 
once  offered  a  lady  an  opera-glass,  which  she  put  to  her 
eyes  and  never  touched  the  adjustment  wheel  that  alters 
the  length  of  the  tubes  and  focuses  the  lenses  on  the 


8  MICROSCOPY  TOR  BEGINNERS. 

actors ;  and  when  she  returned  it  she  said,  "  Thank  you. 
I  don't  like  it  much ;  I  can  see  a  good  deal  better  with- 
out it." 

To  "  get  the  focus  "  it  is  not  really  necessary  to  close 
one  eye,  although  that  is  usually  done.  If  both  eyes 
are  open,  the  one  looking  through  the  lens  becomes  so 
interested  that  the  other  sees  nothing ;  or,  if  you  prefer, 
you  may  say  that  the  brain  becomes  so  interested  in  con- 
templating the  image  formed  on  the  retina  of  the  eye 
examining  the  magnified  object,  that  it  fails  to  note  the 
retinal  impressions  of  the  other.  But  if  one  eye  must 
be  closed,  it  can  be  done,  after  very  little  practice,  with- 
out clapping  your  hand  over  it.  This  applies  equally 
well  to  the  use  of  the  compound  microscope. 

To  focus  a  pocket-lens  hold  the  object  to  be  examined 
in  the  left  hand,  and  while  looking  through  the  glass 
raise  and  lower  it  with  the  right  hand  until  the  magni- 
fied object  appears  clear  and  distinct,  the  outlines  sharp, 
and  without  a  fringe  of  color,  and  the  surface  rough  or 
smooth,  rounded  or  concave,  as  it  indistinctly  appears  to 
the  unaided  eye.  The  focus  cannot  be  obtained  without 
this  experimenting  every  time  the  glass  is  used.  A 
good  plan  is  to  place  the  lens  nearer  the  object  than  you 
know  to  be  necessary,  but  always  without  allowing  the 
two  to  come  in  contact,  and  then  to  slowly  raise  the 
glass  until  the  image  is  distinct,  when  it  will  be  focussed. 
Keep  it  steadily  in  that  position  and  study  the  object. 

The  compound  microscope  (Fig.  2)  consists  of  the 
stand,  the  eye -piece,  and  the  objective,  although  the 


THE   MICROSCOPE   AND   ITS  PARTS.  9 

word,  as  commonly  used,  refers  to  the  entire  combination 
of  brass,  with  or  without  the  magnifying -glasses.     But 


Fig.  2. — A  Compotiud  Microscope. 


without  the  objective  the  microscope  is  only  the  "  stand," 
and  is  practically  useless.    The  stand  alone  generally  in- 
cludes the  tube   or  microscope  body,  the  eye  -  piece, 
I* 


10  MICROSCOPY  FOR  BEGINNERS. 

formed  of  two  lenses  at  the  opposite  ends  of  a  short 
tube  inserted  into  the  upper  end  of  the  body,  the  arm 
supporting  the  body,  the  stage  on  which  the  object  is 
placed  to  be  examined,  the  mirror  to  light  the  object, 
a  movable  circular  plate,  or  diaphragm,  immediately  be- 
neath the  stage,  and  the  foot  that  supports  the  whole. 
The  addition  of  the  objective,  or  magnify  ing  -  glass,  at 
the  lower  end  of  the  body,  makes  the  stand  a  compound 
microscope  of  the  simplest  form.  The  objective  is  so 
named  because  it  is  near  the  object  to  be  examined  when 
the  microscope  is  in  use,  and  the  eye-piece  is  so  called 
because  it  is  then  near  to  the  observer's  eye.  Without 
both  of  these  sets  of  lenses  the  instrument  is  useless. 

The  arm  and  foot  may  be  made  of  either  brass  or 
iron,  and  there  should  be  a  joint  between  them  so  that 
the  upper  parts  of  the  instrument  may  be  inclined.  The 
cheapest  stands  are  made  without  this  arrangement,  and 
they  must  therefore  always  be  used  in  a  vertical  posi- 
tion, the  observer  being  compelled  to  hold  his  head  and 
body  in  a  way  that  soon  becomes  very  wearisome.  An 
iron  arm  and  foot  are  quite  as  useful  as  if  made  of  brass, 
but  no  stand  should  be  selected  without  the  joint  for  in- 
clination. Brass  looks  better,  and  is  much  more  expen- 
sive than  neatly  japanned  iron,  but  is  practically  no 
more  useful. 

The  body  should  be  about  ten  inches  long.  In  the 
less  expensive  stands  it  is  often  made  in  two  parts,  the 
upper  tube  sliding  within  the  other,  so  that  when  it  is 
drawn  out  to  its  full  extent  the  entire  body  will  then  be 


THE  MICROSCOPE  AND  ITS  PARTS.  11 

the  proper  length  to  obtain  the  best  results  from  the  ob- 
jectives. In  such  a  stand,  when  the  inner,  or  "  draw," 
tube  is  pushed  down,  the  microscope  will  have  the  low- 
est magnifying  power  obtainable  with  the  eye-piece  and 
objective  then  in  use ;  when  fully  extended,  the  power 
of  the  objective  will  be  greatly  increased,  so  that  by 
varying  the  length  of  the  body  by  the  use  of  the  "  draw- 
tube,"  many  different  magnifying  powers  may  be  ob- 
tained from  one  objective.  In  some  cases  this  arrange- 
ment may  be  useful ;  it  is  at  least  not  entirely  objec- 
tionable, neither  is  it  very  convenient.  Stands  with  an 
undivided  body  ten  inches  long — the  standard  length — 
also  often  have  a  draw-  tube  by  means  of  which  the  body 
can  be  enormously  lengthened  and  the  magnifying  pow- 
er enormously  increased,  but  usually  with  a  loss  of  some 
good  qualities  in  the  image.  The  addition  is  occasionally 
useful,  but  it  is  not  necessary.  If  the  reader  selects  an 
instrument  with  a  body  of  the  standard  length,  and  he 
finds  that  it  is  without  a  draw-tube,  he  need  not  be 
troubled.  The  stand  will  be  as  valuable  without  as 
with  this  secondary  part. 

The  eye-piece  consists  of  two  lenses  at  the  opposite 
ends  of  a.  short  brass  tube  divided  internally  by  a  dia- 
phragm. The  lens  nearest  the  observer's  eye  when  the 
instrument  is  in  use  is  the  "  eye-glass,"  the  one  at  the 
opposite  extremity  the  "  field-glass."  The  price  of  the 
stand  usually  includes  one  or  more  eye-pieces.  If  but 
one  is  supplied,  it  will  generally  be  the  lowest  power, 
the  two-inch  or  "A;"  if  two,  the  one-and-one-half  or 
2 


12  MICROSCOPY  FOR  BEGINNERS. 

one-inch,  often  also  called  "  B  "  or  "  C,"  will  be  added. 
Opticians  also  make  £,  f ,  J,  and  even  ^  inch  eye-pieces, 
most  of  which  are  for  special  kinds  of  microscopical 
work,  their  magnifying  power  being  enormous  and  the 
result  almost  worthless ;  indeed,  these  very  high  power 
eye-pieces  are  usually  to  be  avoided.  On  no  account 
should  they  be  selected  by  the  beginner  in  microscopy. 
Every  purchaser  of  a  stand  should  insist  upon  having 
the  two-inch,  if  he  can  have  but  one,  as  it  is  always  use- 
ful, and  is  all  he  will  need  for  a  long  time,  or  until  he 
desires  to  use  an  eye- piece  micrometer  for  the  meas- 
urement of  microscopic  objects,  when  he  can  add  the 
one-inch,  or  "  B,"  ocular  to  his  stand. 

The  lower  opening  in  the  body  always  carries  a  screw 
to  receive  the  one  on  the  upper  end  of  the  objective. 
Several  years  ago  the  size  of  these  screws  varied  widely 
in  stands  and  objectives  of  different  makers,  so  that  if 
the  student  desired  an  objective  of  different  make  from 
those  accompanying  his  instrument,  he  was  forced  to 
buy  a  little  piece  of  apparatus  called  an  adapter,  one  end 
of  which  was  made  to  screw  into  the  microscope  body, 
the  other  to  receive  the  objective.  At  the  suggestion, 
however,  of  the  Royal  Microscopical  Society  of  London, 
all  objectives  and  stands  now  have  screws  of  the  size 
recommended  by  that  society,  and  therefore  called  the 
"  society-screw."  Only  the  very  cheapest  stands  of  the 
present  day,  or  those  having  the  least  value  as  instru- 
ments for  serious  investigation,  are  without  this  screw, 
and  they  are  usually  supplied  with  what  are  termed 


THE   MICROSCOPE  AND   ITS  PARTS.  13 

French  triplets.  These  are  miserable  lenses  that  should 
always  be  shunned,  as  they  will  do  the  observer  more 
injury  than  much  time  can  remedy. 

It  is  true  that  before  the  optician,  especially  before 
the  American  optician,  began  to  make  really  good  ob- 
jectives at  moderate  cost,  these  French  triplets  were 
extensively  used,  and  are  said  to  have  done  some  good 
work.  But  at  what  expense  ?  Not  at  the  expense  of 
any  great  amount  of  knowledge  or  skill  in  their  manu- 
facture, for  the  lenses  were  ground,  mounted  singly,  and 
then  combined  in  an  experimental  way :  two  or  three 
were  selected  at  random  from  a  basketful,  screwed  to- 
gether, and  examined  on  a  microscope.  If  the  result 
was  considered  satisfactory,  all  was  well ;  if  not,  one  or 
more  of  the  lenses  was  replaced  by  others  also  selected 
at  random,  and  the  experiments  were  continued  until 
the  objective  was  considered  passable  and  salable. 
Such,  at  least,  is  the  credible  story.  Their  expense, 
therefore,  was  not  in  the  making ;  it  was  in  the  imper- 
fect image,  in  the  great  loss  of  light,  in  the  injury  to 
the  eye  due  to  the  strain  caused  by  the  absence  of  sharp- 
ness and  brilliancy  characteristic  of  the  image  formed 
by  even  low-priced  American  objectives,  and  in  the  time 
wasted  while  unconsciously  forming  erroneous  conclu- 
sions from  the  objects  so  imperfectly  seen.  The  writer 
is  somewhat  emphatic  on  this  point.  He  knows  where- 
of he  speaks,  for  he  began  the  use  of  the  microscope 
with  French  triplets,  and  employed  them  for  years,  be- 
cause he  was  ignorant  and  had  no  teacher.  What  the 


14  MICROSCOPY  FOR  BEGINNERS. 

cost  was  to  him  lie  knows  only  too  well.  To  the  young 
student  who  longs  for  a  microscope,  I  am  almost  tempt- 
ed to  say,  if  you  cannot  afford  the  cheapest  suitable  low- 
power  American  objective,  if  you  must  have  the  ordi- 
nary French  triplet  or  none,  take  none.  It  is  a  hard 
fate,  but  is  not  life  itself  hard  ?  Fortunately,  however, 
these  inferior  commercial  lenses  are  not  extensively  in 
the  market  at  the  present  day.  Yet  the  purchaser  of  a 
microscope  already  fitted  out  with  objectives,  should 
inquire  whether  he  is  buying  French  triplets.  If  so, 
then  as  his  experience,  knowledge,  and  skill  increase,  so 
will  his  dissatisfaction  increase.  An  intelligent  boy  had 
been  using  these  poor  lenses  for  some  time,  and  doing 
work  that,  under  the  circumstances,  was  commendable, 
when  he  for  the  first  time  looked  through  a  good  low- 
power  (one-inch)  objective.  After  a  momentary  exam- 
ination, he  glanced  at  me  in  a  wondering  way  as  he 
said  :  "  How  beautifully  bright  and  clear  it  looks !  My 
microscope  is  different.  I  think  it  needs  cleaning !" 

Modern  objectives  are  the  result  of  the  most  consum- 
mate skill  of  the  accomplished  optician.  There  is  no 
chance  work  in  his  methods.  Every  curve  is  mathe- 
matically exact,  and  is  calculated  and  positively  known 
before  the  glass  comes  to  the  grinding-tool.  Objectives 
are  usually  a  combination  of  several  lenses,  but  the 
union  is  not  accidentally  perfected.  The  maker's  knowl- 
edge of  abstruse  optics  tells  him  the  precise  result  to 
expect  from  the  combination  of  lenses  of  certain  forms 
made  from  glass  of  a  certain  chemical  composition.  He 


THE   MICROSCOPE   AND   ITS  PARTS.  15 

is  the  master ;  his  objective  is  a  masterpiece.  The  own- 
er of  a  good  objective  must  not  treat  it  carelessly.  He 
should  treasure  it,  for  it  is  not  a  common  thing.  "When 
not  on  the  stand  in  use,  it  should  be  kept  in  the  brass 
box  supplied  for  that  purpose,  and  it  should  never  be 
left  on  the  stand  when  not  in  actual  employment. 

That  part  of  the  brass  mounting  of  the  objective 
which  bears  the  screw  is  the  back ;  the  opposite  end  that 
shows  a  small  flat  surface  of  glass  is  the  front,  or,  as  it  is 
often  styled,  the  front  lens.  The  glass  of  this  part  is 
soft  and  easily  scratched,  therefore  take  care  not  to 
let  it  touch  anything  hard ;  especially  avoid  any  gritty 
substance,  or  dirty  rag  that  may  hold  a  minute  parti- 
cle of  sand  or  hard  dust.;  and  never  touch  it  with  the 
lingers,  as  the  oily  exudation  from  the  skin  will  soil 
it  and  interfere  with  the  clearness  and  beauty  of  the 
image.  If  the  front  lens  becomes  accidentally  stained, 
or  soiled  by  long  use,  the  objective  should  be  sent  to  its 
maker,  who  can  clean  it  without  the  great  risk  that  its 
owner  would  expose  it  to  if  an  attempt  should  be  made 
to  wipe  the  glass.  If  fine  dust  adheres  too  closely  to 
be  dislodged  by  the  breath,  ravel  out  the  edge  of  a  piece 
of  very  clean  old  linen  or  muslin,  and  with  the  fringe 
thus  obtained  gently  sweep  the  surface. 

"When  the  objective  is  to  be  taken  from  its  box,  un- 
screw the  cover  and  tip  the  lens  into  the  palm  of  the 
left  hand,  supporting  it  with  the  fingers ;  pick  it  up 
with  the  thumb  and  finger  of  the  right  hand  against  the 
sides  of  the  tube  or  brass  mounting,  and  it  will  be  ready, 


16  MICROSCOPY  FOR  BEGINNERS. 

when  reversed,  to  be  screwed  to  the  stand.  If  it  is  not 
to  be  returned  to  the  box  immediately  after  use,  as  will 
often  happen  if  the  student  has  more  than  one,  and  he 
desires  to  examine  the  object  with  another  power,  stand 
it  on  its  screw  end  on  the  table,  and  to  protect  it  from 
dust  invert  its  box  over  it.  The  latter  can  be  lifted  off 
in  a  moment,  and  the  objective  will  then  be  ready  to 
be  picked  up  as  before. 

What  objectives  should  the  beginner  select  ?  If  pos- 
sible, he  should  have  two,  a  low  and  a  moderately  high 
magnifying  power.  If  unable  to  purchase  both  at  once, 
let  him  by  all  means  first  take  what  is  called  the  one- 
inch  objective ;  if  he  can  also  buy  a  high  -  power,  the 
£  or  %  will  be  the  proper  glass.  But  for  this  he  can 
wait.  There  is  so  much  to  be  examined  with  the  one- 
inch  objective  that,  for  a  long  time,  he  will  scarcely  feel 
the  need  of  another.  The  inch,  if  properly  selected, 
need  not  be  expensive,  but  it  should  be  a  good  and  sat- 
isfactory glass,  not  only  at  the  outset,  but  when  the  stu- 
dent becomes  an  expert  microscopist ;  it  will  then  always 
be  useful.  Such  objectives  are  made  by  several  Ameri- 
can opticians,  and  included  in  what  they  call  their  "  Stu- 
dents' Series."  "When  in  focus,  the  distance  between  the 
front  lens  and  the  surface  of  the  object — the  "working 
distance  " — is  large,  so  there  will  be  no  trouble  in  using 
it;  and  with  the  two-inch,  the  "A"  eye-piece,  the  mag- 
nifying power  will  be  about  forty-five  diameters,  or  a 
little  more  than  two  thousand  times. 

After  the  student  has  been  using  the  one-inch  objec- 


THE  MICROSCOPE  AND  ITS  PARTS.  17 

tive  for  some  time,  and  his  eye  lias  become  educated,  he 
will  begin  to  catch  glimpses  of  minute  objects  beyond 
the  ability  of  the  low-power  glass  to  properly  exhibit. 
Then  he  will  wish  for  something  more,  so  that  he  can 
look  deeper  into  the  little  things  of  nature.  What  shall 
it  be  ?  The  opticians  make  ^,  T^,  and  even  -^  inch  ob- 
jectives, which  magnify  enormously,  cost  frightfully, 
and  can  be  successfully  used  only  by  accomplished  mi- 
croscopists  on  large  and  first-class  stands.  To  the  be- 
ginner, even  after  considerable  experience  with  the 
low-power,  any  objective  higher  than  the  £  or  -§-  will  be 
useless.  With  these  glasses  he  will  be  well  equipped 
for  quite  extensive  microscopical  study,  until  he  is  ready 
to  undertake  original  work  in  some  unexplored  depart- 
ment of  science,  or  in  some  partially  neglected  corner, 
of  which  there  are  many  in  every  scientific  field,  how- 
ever well  cultivated.  Like  the  one -inch,  the  %  or  -J- 
will  always  be  useful.  As  the  observer's  eye  becomes 
better  educated,  when  it  learns,  as  it  will,  to  see  minute 
parts  of  delicate  objects,  which  at  the  start  were  entire- 
ly, overlooked,  the  high -power  objective  will  not  be 
thrown  aside,  the  student  will  not  become  disgusted 
with  it  as  lie  would  with  a  high-power  French  triplet, 
but  his  quickened  sight  will  again  catch  glimpses  of 
beauty  to  be  examined,  and  mystery  to  be  unravelled, 
which  are  beyond  the  power  of  his  best  objective,  and  he 
will  almost  unconsciously  have  advanced  another  step. 

Personally  the  writer  prefers  the  ^  inch  objective  to 
the  ^,  and  such  a  glass  need  not  be  expensive  to  be  good 


18  MICROSCOPY  FOU  BEGINNERS. 

(several  opticians'  "Students'  Series"  include  them),  the 
working  distance  is  not  too  short,  or  need  not  be,  and 
with  the  two-inch  eye-piece  it  will  give  a  magnifying 
power  of  about  two  hundred  and  fifty  diameters. 

"The  coarse  adjustment"  is  the  expression  usually 
applied  to  the  rapid  movement  of  the  body  produced 
by  turning  the  large  milled  heads,  one  of  which  is  on 
each  side  of  the  instrument.  It  is  used  in  focussing, 
that  is,  in  obtaining  a  distinct  image  of  the  object  when 
seen  through  the  eye-piece  and  objective.  The  image 
then  appears  surrounded  by  a  circle  of  light  called  the 
"field  of  view,"  or  simply  "the  field."  Yery  few,  ex- 
cept the  small,  vertical  "boys'  microscopes,"  and  some 
of  the  cheapest  and  least  desirable  American  or  English 
stands,  are  without  the  coarse  adjustment.  Occasionally 
a  stand  will  be  seen  in  which  this  part  is  replaced  by  a 
broad,  cloth-lined,  or  tightly-fitting  collar,  through  which 
the  body  slides,  the  movement  being  made  by  hand. 
This  is  very  unsatisfactory,  and  such  stands  should  be 
avoided,  if  possible,  as,  sooner  or  later,  the  body  is  sure 
to  be  suddenly  pushed  too  far  down,  the  objective  then 
coming  in  contact  with  the  object :  an  accident  to  be  al- 
ways guarded  against  with  the  greatest  care,  as  the  ob- 
jective, or  the  object,  or  both,  may  be  injured.  If  the 
object  is  destroyed  it  may  possibly  be  replaced,  but  a 
scratched  or  broken  objective  can  be  remedied  only  by 
buying  a  new  one.  Of  course  the  microscope  body  may, 
by  a  careless  student,  be  forced  against  the  object  by 
the  use  of  the  milled  heads,  and  equally,  of  course,  a 


THE  MICROSCOPE  AND   ITS  PARTS.  19 

man  may  fill  his  stomach  with  gravel-stones  or  powder- 
ed glass ;  but  no  sane  man  will  so  maltreat  that  organ, 
and  no  sane  microscopist  will  so  maltreat  his  objective 
as  to  drive  it  against  the  object  on  the  stage  when  the 
risk  is  so  great. 

The  only  proper  way  to  use  the  coarse  adjustment  is 
to  always  focus  upward.  When  the  object  to  be  ex- 
amined has  been  placed  on  the  stage,  and  the  light  from 
the  mirror  is  properly  arranged,  the  microscope  body, 
with  the  eye-piece  and  objective,  is  racked  downward  by 
means  of  the  milled  heads  until  the  front  of  the  objec- 
tive almost  touches  the  object,  the  observer  carefully 
watching  that  they  do  not  come  in  contact.  Then  place 
the  eye  at  the  eye-piece,  and  nothing  will  be  visible  ex- 
cept the  brightly  illuminated  field  of  view ;  but,  while 
looking  into  the  microscope,  slowly  raise  the  body  until 
the  image  appears  sharp  and  clear,  in  other  words  until 
the  objective  is  focussed.  It  makes  no  difference  wheth- 
er the  distance  between  the  front  lens,  when  focussed, 
and  the  object  is  two  inches  or  the  one-hundredth  part 
of  one  inch,  always  rack  the  objective  down  while  you 
are  looking  at  it,  and  focus  upward  while  you  are  look- 
ing through  it.  This  is  the  single  rule  that  must  never 
be  forgotten.  It  has  been  said  in  a  joking  way,  "that 
nothing  will  throw  a  microscopist  into  a  chill  more 
quickly  than  to  see  a  friend  look  into  his  microscope 
and  focus  down  with  the  coarse  adjustment."  Yet  men 
who  ought  to  know  better  have  been  seen  to  do  this 
reprehensible  thing. 


20  MICROSCOPY  FOR  BEGINNERS. 

In  the  older  stands  a  single  small  milled  head  will  be 
found  on  the  front  of  the  body  near  the  lower  end,  just 
above  the  society-screw.  In  more  recent  stands  it  will 
be  on  the  arm  at  the  back  of  the  instrument.  This  is  the 
"fine  adjustment  screw ;"  and  although  it  adds  somewhat 
to  the  cost,  it  should  always  be  on  the  stand  if  the  pur- 
chaser desires  to  use  even  moderately  high-power  objec- 
tives. For  low-powers  it  is  not  necessary.  The  fine  ad- 
justment screw  is  so  made  that  by  turning  its  milled  head 
the  objective,  if  the  adjustment  is  at  the  front,  or  the 
entire  body,  if  it  is  at  the  back,  is  slowly  raised  or  low- 
ered. When  the  high-power  objective  has  been  imper- 
fectly focussed  by  racking  the  body  upward^  it  seldom 
happens  that  the  image  is  as  distinct  as  is  desirable ; 
therefore  the  microscopist,  by  a  few  gentle  turns  of  the 
fine  adjustment  screw,  raises  or  lowers  the  objective,  un- 
til the  magnified  image  has  its  outlines  as  sharply  de- 
fined as  the  figures  in  the  best  steel  engravings.  With 
the  one-inch  objective,  or  others  still  lower  (two,  three, 
or  even  four  inch),  the  focus  can  be  accurately  obtained 
by  the  coarse  adjustment  alone,  but  with  the  £  or  £  the 
fine  adjustment  must  always  be  used. 

It  is  a  great  mistake  made  by  some  who  ought  to 
know  better,  to  try  to  examine  an  object  not  distinctly 
in  focus.  In  such  cases  the  strain  on  the  eye  is  severe 
and  injurious,  while  the  pleasure  of  examining  the 
preparation  is  much  lessened.  The  changes  made  for 
the  better  by  a  few  delicate  touches  of  the  fine  adjust- 
ment can  be  appreciated  only  when  seen.  Always  try 


THE  MICROSCOPE  AND  ITS  PARTS.  21 

to  have  the  image  as  distinct  as  possible.  If  in  doubt 
as  to  the  focus,  after  obtaining  what  seems  to  be  a 
moderately  good  appearance,  give  the  fine  adjustment  a 
turn  or  two  one  way  or  the  other,  noticing  whether  the 
image  becomes  sharper  in  outline  and  clearer  in  its  gen- 
eral aspect,  or  whether  it  grows  cloudy  and  indistinct. 
If  the  last,  the  focus  has  not  been  improved,  and  was 
probably  correct  at  first.  A  very  little  experience  will 
make  the  beginner  an  expert  in  this  important  matter. 

The  stage,  on  all  but  the  largest  and  most  expensive 
instruments,  is  a  square  or  circular  piece  of  thin  metal, 
with  a  large  central  circular  opening  for  the  passage  of 
the  light  from  the  mirror.  Sometimes  the  metal  stage 
has  a  glass  plate  made  to  slide  over  it  easily.  This  is  a 
convenience  and  a  desirable  luxury,  but  it  is  by  no 
means  necessary.  The  strip  of  glass  that  bears  the  ob- 
ject to  be  examined  can  just  as  readily  be  slipped  about 
under  the  objective  by  the  fingers  directly,  as  it  can  be 
if  supported  on  this  movable  glass  stage.  These  finger 
movements  require  a  little  practice,  but  the  student  will 
so  soon  become  accustomed  to  them  that  he  will  change 
the  position  of  the  object  without  consciously  thinking 
of  it,  and  his  touch  will  become  so  delicate  that  he  will 
be  able,  with  the  slightest  pressure,  to  move  the  object 
for  a  distance  so  small  that  it  would  be  invisible  to  the 
naked  eye.  All  this  is  rather  awkward  at  first,  because 
the  object  must  be  moved  while  the  eye  is  looking 
through  the  microscope ;  and,  in  addition,  if  it  is  to  be 
pushed  to  what  appears  to  be  the  left-hand  side  of  the 


22  MICROSCOPY  FOR  BEGINNERS. 

field  of  view,  it  must  actually  be  pulled  towards  the  ob- 
server's right  hand ;  and  if  the  image  is  to  travel  up  the 
field,  that  is,  away  from  the  observer  as  he  sits  at  the 
microscope,  the  object  must  really  be  slipped  towards 
him,  because  the  lenses  reverse  the  image.  This  seems  a 
very  complicated  proceeding,  but  it  soon  becomes  the 
easiest  thing  imaginable.  At  the  first  trial  the  object 
will  be  sure  to  leap  entirely  out  of  the  field,  because  it 
will  be  too  rapidly  moved,  and  the  motion  is  magnified 
as  well  as  the  object ;  but  the  student  will  become  so 
expert  that  before  very  long  he  will  be  able  to  make 
on  the  stage  of  his  microscope  complicated  dissections 
with  fine  needles  of  the  internal  organs  of  the  house- 
fly, or  some  other  equally  small  insect. 

The  stage  will  probably  have  two  springs  on  the  up- 
per surface,  one  on  each  side.  These  "spring  clips" 
are  to  keep  the  glass  slide  holding  the  object  in  position, 
unless  intentionally  moved.  The  slide  is  put  under  the 
clips,  and  the  object,  provided  it  is  itself  stationary,  will 
remain  in  the  field,  where  it  can  be  examined  quietly 
and  comfortably. 

The  diaphragm  should  always  be  present.  It  will  be 
pierced  near  the  edge  with  a  series  of  openings  of  vari- 
ous sizes,  to  modify  the  amount  of  light  thrown  on  the 
object,  the  largest  opening  admitting  the  greatest 
amount.  The  beginner  will  at  first  be  disposed  to  use 
too  much  light ;  indeed  this  is  a  fault  of  many  older  mi- 
croscopists.  More  can  be  seen  with  a  moderately  light- 
ed field  than  when  the  eye  is  dazzled  and  half  blinded 


THE  MICROSCOPE  AND  ITS  PARTS.  23 

by  a  fierce  glare.  Such  a  blaze  is  objectionable,  not 
only  because  it  tends  to  obscure  the  finer  parts  of  the 
object,  but  it  may  lead  the  student  or  his  friends  to 
condemn  the  microscope  as  injurious  to  the  sight — an 
unjust  accusation  more  than  once  made.  If  too  much 
light  is  undesirable,  do  not  go  to  the  opposite  extreme 
and  strain  the  eye  by  forcing  it  to  work  in  semi-dark- 
ness. Keep  the  field  sufficiently  lighted  to  be  pleasant 
to  the  sight.  Turn  the  diaphragm  until  the  opening 
giving  the  most  agreeable  effect  and  illuminating  the 
object  enough  to  show  the  parts  clearly  is  under  the 
centre  of  the  stage  opening.  If  the  object  is  very  thick 
or  opaque,  more  light  will  be  needed  than  if  it  were  per- 
fectly transparent ;  in  such  cases  use  a  larger  diaphragm 
opening. 

The  mirror  is  one  of  the  most  important  parts  of  the 
stand.  It  should  have  both  a  concave  and  a  plane  sur- 
face, and  it  ought  not  to  be  less  than  two  inches  in  di- 
ameter, so  that  it  may  reflect  enough  light  and  be  easily 
handled.  In  the  newest  styles  of  stands  the  mirror  is 
arranged  to  swing  from  side  to  side,  so  as  to  throw  an 
oblique  beam  of  light  on  the  object,  as  well  as  to  rise 
above  the  stage,  so  that  light  may  be  reflected  down 
upon  an  opaque  specimen,  since  it  is  used  below  the 
stage  for  the  illumination  of  transparent  substances  only. 
This  swinging  arrangement  is  very  convenient,  and 
should  be  had  if  possible.  It  is,  however,  not  absolute- 
ly necessary,  as  similar  illumination  of  opaque  bodies 
can  be  obtained  by  the  "bull's  eye  condensing  lens,"  a 


24:  MICROSCOPY  FOR  BEGINXERS. 

rather  expensive  piece  of  apparatus,  and  somewhat  diffi- 
cult to  manipulate  successfully.  But  as  the  newest  and 
best  stands  have  the  swinging  mirror,  the  condensing 
lens  need  not  be  described,  especially  since  the  beginner 
will  not  care  to  examine  many  opaque  objects  that  will 
demand  stronger  illumination  than  that  of  ordinary  dif- 
fused daylight  or  common  lamplight. 

When  ready  to  examine  an  object,  the  stand  is  placed 
near  the  window,  or,  if  at  night,  the  lighted  lamp  is 
stood  near  the  instrument  on  the  left-hand  side  and  one 
or  two  inches  in  front  of  the  mirror,  and  the  objective 
is  screwed  on.  The  microscope  is  inclined  at  a  conven- 
ient angle  ;  the  mirror  is  moved  in  various  directions, 
until  the  light  is  reflected  from  a  white  cloud,  if  possi- 
ble, or  from  the  lamp,  onto  the  front  of  the  objective, 
where  it  can  be  easily  seen.  The  eye  is  then  placed  at 
the  eye-piece,  and  if  the  field  is  but  partially  lighted, 
as  it  probably  will  be,  perhaps  one-half  of  it  being  in 
shadow,  or  only  a  faint  trace  of  light  visible  at  one  side, 
the  mirror  is  slowly  moved  until  the  field  is  brightly 
and  evenly  illuminated,  when  every  part  of  the  circular 
bright  space  within  the  instrument  is  as  well  lighted  as 
every  other  part.  The  position  of  the  diaphragm  is 
then  changed,  to  be  further  altered,  if  necessary,  after 
the  object  has  been  placed  on  the  stage.  This  even  il- 
lumination may  at  first  be  a  little  troublesome  to  obtain, 
but  as  in  so  many  other  actions  in  connection  with  the 
microscope,  a  very  little  practice  will  overcome  every 
difficulty.  The  fingers  are  soon  taught;  they  speed- 


THE  MICROSCOPE  AND   ITS  PARTS.  25 

ily  do  their  work  without  their  owner's  conscious  bid- 
ding. 

The  specimen  to  be  studied  may  be  permanently  pre- 
served, or  "mounted,"  on  a  slip  of  glass,  under  a  thin 
cover  and  surrounded  by  Canada  balsam,  glycerine,  or 
some  other  preservative,  thus  forming  preparations 
called  "  slides/'  or  "  mounted  slides,"  the  plain  piece  of 
glass  without  the  object  being  a  "slip."  The  addition 
of  the  object  therefore  changes  the  slip  into  a  slide.  It 
is  well  to  remember  this  distinction  in  talking  with  the 
dealers  or  sending  orders  by  mail. 

Slides  can  be  made  by  the  student,  although  to  do  the 
work  neatly  and  well  demands  some  skill  and  considera- 
ble preliminary  study  of  the  object  before  it  can  be  pre- 
pared for  the  mounting  processes ;  or  the  slides  may  be 
purchased.  It  is  much  better  arid,  in  the  end,  more  sat- 
isfactory to  the  owner  of  the  slides  to  prepare  them 
himself.  Certain  rare  objects,  if  desired,  must  be  bought 
already  mounted,  but  any  small  object  naturally  dry 
can  be  so  easily  mounted  by  placing  it  in  a  drop  of  Can- 
ada balsam  from  the  druggist's,  and  covered  by  a  cover 
of  thin  glass  from  the  optician's,  that  for  the  beginner 
to  spend  his  money  for  "  the  foot  of  a  fly,"  "  dust  from 
a  butterfly's  wing,"  "  the  sting  of  a  bee,"  or  similar 
slides  crowding  the  dealers'  lists  and  drawers,  is  non- 
sense, unless  he  lives  alone  in  the  wilderness,  and  is  ig- 
,  norant  of  the  appearance  of  a  slide ;  in  such  a  case,  to 
buy  the  mounted  foot  of  a  fly  may  be  useful  to  show 
what  is  to  be  aimed  at  in  the  preparation  of  ordinary 


26  MICROSCOPY  FOR  BEGINNERS. 

objects.  A  few  properly  mounted  slides,  however,  usu- 
ally accompany  the  stand  as  specimens,  or  the  dealer 
will  supply  them  if  asked.  It  is  better  to  do  than  to 
buy,  and  so  much  has  been  written  on  the  subject  of 
microscopic  mounting,  and  indeed  all  advanced  workers 
with  the  microscope  are  such  "  good  fellows,"  they  are 
always  so  generous  in  giving  away  for  the  asking  infor- 
mation that  has  cost  much  time  and  labor  to  obtain,  that 
the  young  student  need  never  despair,  nor  be  at  a  loss 
as  to  where  to  go  for  help,  if  he  possesses  the  name  and 
address  of  some  microscopist  and  a  postage-stamp  or 
two.  Cheap  little  hand-books  on  the  subject  are  acces- 
sible, microscopists  are  numerous  and  willing,  so  why 
should  the  beginner  ever  be  discouraged  ?  and  why  should 
he  buy  what  he  can  make  ?  It  always  adds  a  zest  to 
this  work  if  the  worker  can  make  his  own  tools,  and  es- 
pecially if  he  can  prepare  his  own  objects.  Almost  ev- 
ery tool  needed  at  the  beginning  can  be  made  at  home. 
Slides  must  be  made  at  home  if  one  desires  to  examine 
any  of  the  endless  variety  of  the  invisible  animal  and 
vegetable  life  with  which  the  great  world  teems.  All 
the  objects  referred  to  in  this  book  can  be  studied  when 
only  temporarily  mounted ;  indeed,  no  method  of  pre-. 
serving  some  of  them  has  yet  been  discovered  or  invent- 
ed. They  must,  therefore,  be  studied  alive  or  not  at 
all.  And  for  the  beginner  this  is  not  only  the  easiest, 
but  it  is  the  most  inspiring  way. 

Some  things  can  be  examined  when  dry.     Such  an 
object  is  simply  laid  on  a  slip,  placed  under  the  spring 


THE   MICROSCOPE   AND  ITS  PARTS.  27 

clips,  and  the  low-power  objective  used.  The  ripe  seeds 
of  wild  plants  are  easily  studied  in  this  way,  and  some 
of  them  are  marvellously  beautiful.  Small  insects  can 
also  be  looked  at  when  dry,  but  the  result  is  not  always 
entirely  satisfactory  unless  they  are  viewed  as  opaque 
objects.  Usually  most  objects  appear  better  and  show 
more  of  their  structure  if  examined  under  a  disk  of  thin 
glass  and  surrounded  by  water.  But  seeds,  scales  from 
butterfly's  wings,  and  many  other  things,  can  be  viewed 
and  preserved  in  a  dry  state  by  enclosing  them  in  a  cell 
with  a  thin  glass  cover  fastened  above.  This  "  cell " 
and  "cover"  and  fastening  process  will  be  described 
presently. 

All  plants  and  animals  living  in  water  must  be  ex- 
amined in  water.  To  dry  them  and  expect  to  learn 
anything  about  them,  or  even  to  obtain  a  correct  idea 
of  their  true  appearance,  is  a  waste  of  time,  and  worse. 
When  your  wet  specimens  get  dry  on  the  slide,  and  you 
think  you  are  seeing  some  wonderful  things,  add  a  drop 
of  water,  and  save  yourself  a  probable  blunder.  Cer- 
tain objects,  naturally  dry,  will  look  better  and  will  re- 
veal their  secrets  sooner  if  examined  wet.  This  is  due 
to  optical  reasons  not  necessary  to  explain  here.  The 
observer,  if  he  is  seeking  information,  and  not  merely 
pretty  things  to  please  the  eye  and  the  aesthetic  fancy, 
will  do  well  if  he  examines  naturally  dry  objects  both 
in  and  out  of  water;  but  things  naturally  wet  must 
never  be  seriously  studied  in  a  dry  condition. 

The  most  convenient  size  for  slips  is  three  inches  in 


28  MICROSCOPY  FOR  BEGINNERS. 

length  by  one  in  width.  Some  microscopists  use  and 
recommend  them  two  and  one-half  inches  long  by  one- 
half  an  inch  wide,  and  this  will  probably  be  the  size  of 
the  slides  accompanying  the  student's  stand.  They  are, 
however,  much  too  small ;  it  will  be  better  for  the  be- 
ginner to  at  once  select  the  standard,  three  inches  by 
one  inch,  size.  These  can  be  bought,  and  the  writer 
would  advise  that  they  should  be,  as  the  edges  will  then 
be  ground  smooth  and  perhaps  polished,  although  the 
last  is  not  necessary.  Slips  can  be  cheaply  cut  by  any 
glass-dealer  who  has  a  diamond  or  glass-cutting  wheel, 
and  if  thus  made,  the  best,  whitest,  smoothest,  and  thin- 
nest glass  should  be  selected.  The  rough  edges  of  the 
home-made  slips,  however,  are  not  pleasant  to  handle, 
the  student  who  uses  them  taking  the  risk  of  cut  fin- 
gers. Otherwise,  unless  they  have  a  green  color,  they 
are  as  useful  as  the  more  expensive  ones  sold  by  the 
dealers. 

A  drop  of  water  on  a  slip  of  smooth  glass  is  not  easi- 
ly kept  in  position.  "When  the  slide  is  placed  on  the 
stage,  and  the  microscope  is  inclined  for  use,  the  water 
will  surely  run  away,  and  probably  carry  the  object  with 
it.  If  the  microscope  is  not  inclined,  the  convex  sur- 
face of  the  drop,  and  its  tremulous  movements,  will  so 
affect  the  light  that  the  image  will  be  distorted,  and  the 
observer  will  obtain  erroneous  impressions.  A  piece  of 
glass  placed  over  the  water  will  flatten  the  surface,  the 
distortion  of  the  image  will  be  partially  counteracted, 
and  capillary  attraction  will  keep  the  liquid  from  en- 


THE  MICROSCOPE  AND  ITS  PARTS.  29 

tirely  running  away.  But  ordinary  glass  is  too  thick 
for  this  purpose,  consequently  thin  glass  prepared  for 
microscopical  use  must  be  purchased.  This  varies  in 
thickness  from  No.  1,  measuring  about  r^  to  ^ihr  inch 
or  thinner ;  No.  2,  about  T^ ;  and  'No.  3,  from  ^V  to  TV 
inch.  ~No.  2  glass  will  be  the  proper  thickness.  It  can 
be  obtained  either  in  circles  of  various  sizes  or  in 
squares.  For  permanent  mounts  the  circles  are  usually 
employed.  For  temporary  purposes,  for  the  examina- 
tion of  an  object  that  is  not  to  be  preserved  for  future 
use,  or  when  many  examinations  of  separated  parts  of 
the  same  large  specimen  are  to  be  made,  the  writer  much 
prefers  thin  squares,  and  always  uses  them.  They  are 
pleasanter  to  handle,  they  are  more  easily  wiped  dry 
and  with  less  liability  to  breakage,  and  their  cost  is 
somewhat  less  than  circles  of  the  same  thickness. 

The  matter  of  cleaning  thin  glass  is  an  important  one, 
and  unless  the  "  knack "  is  soon  learned,  the  beginner 
will  be  surprised  at  the  rapidity  with  which  his  covers 
will  disappear.  This  skill,  however,  is  readily  attained. 
The  writer  has  had  the  same  thin  square  of  No.  1  glass 
in  use  for  three  months  continuously,  frequently  remov- 
ing and  reapplying  it  during  the  five  or  six  hours  of 
daily  evening  work  in  which  it  did  important  service, 
and  in  the  end  he  became  quite  attached  to  it  as  to  a 
good  friend.  But  a  hasty  move  while  cleaning  it,  or  a 
little  undue  pressure,  finally  sent  it  on  the  way  that -thin 
covers  often  travel.  To  clean  without  much  risk  of 
breaking,  take  the  square  with  two  opposite  edges,  that 


30  MICROSCOPY  FOR  BEGINNERS. 

is,  with  the  edges  where  the  glass  was  cut,  between  the 
thumb  and  finger  of  the  left  hand,  and  with  a  piece  of 
soft,  old  muslin  held  smoothly  over  the  thumb  and  fore- 
finger of  the  right  hand,  gently  wipe  both  surfaces  at 
once,  rotating  the  square  when  necessary.  The  secret 
of  success  is  care,  gentleness,  and  no  wrinkles.  It  was 
probably  a  wrinkle  in  the  muslin  that  ruined  my  three 
months'  old  pet  cover.  But  a  punishment  is  a  good 
thing  sometimes ;  the  microscopist  who  should  begin  to 
think  that  he  was  skilful  enough  to  avoid  breakage  of 
covers  for  more  than  three  months,  might  become  in- 
sufferably conceited  and  a  nuisance  to  his  friends. 

But  a  glass  square,  however  thin,  dropped  on  a  deli- 
cate animal  or  plant  will  often  crush  it,  and  destroy  all 
resemblance  to  anything  that  ever  lived.  Some  means 
must  be  devised  for  supporting  it  at  a  very  short  dis- 
tance above  the  slip,  so  that  the  living  creatures  may 
have  room  to  move  about,  and  the  plants  may  not  be 
too  much  flattened.  This  is  done  by  making  a  ring  of 
cement  on  the  slip,  and  thus  enclosing  a  circular  space 
called  a  cell,  which  can  be  made  of  any  depth  by  apply- 
ing more  cement  after  the  first  application  has  dried,  or 
by  using  the  cement  very  thickly. 

The  opticians  offer  several  kinds  of  cement  for  sale, 
all  of  which  are  useful  for  special  purposes ;  but  the  one 
that  seems  most  convenient,  and  one  that  can  be  easily 
prepared  by  the  beginner,  is  simply  shellac  dissolved  in 
alcohol.  The  solution  can  be  made  as  thick  as  is  desired 
by  allowing  some  of  the  alcohol  to  evaporate,  or  it  can 


THE   MICROSCOPE  AND   ITS  PARTS.  31 

be  thinned  by  the  addition  of  more.  It  should  be  thick 
enough  to  flow  freely  from  a  small  camel's-hair  brush, 
but  not  so  thin  as  to  spread  in  an  irregular  film  over  the 
glass.  As  shellac  dissolves  slowly  in  alcohol,  it  is  better 
to  add  more  of  the  latter  than  will  be  needed,  and  to 
thicken  the  solution  by  evaporation.  It  will  keep  for 
any  length  of  time  in  a  tightly  closed  bottle. 

A  ring  can  be  built  up  with  a  camel's-hair  brush,  and 
this  cement,  either  by  the  hand  alone,  or  by  a  little  ma- 
chine called  a  "  turn-table,"  manufactured  for  the  pur- 
pose. These  turn-tables  are  as  nice  and  neat  and  beau- 
tiful as  can  be  imagined,  and  they  cost — the  cheapest 
that  I  can  find  in  the  catalogues  costs  $2.50.  They 
spin  perfect  circles  exactly  in  the  centre  of  the  slip,  and 
the  result  is  very  pretty  and  very  desirable  if  the  be- 
ginner can  afford  one,  but  he  can  get  along  right  well 
without.  If  you  have  none,  draw  in  the  centre  of  a 
strip  of  white  pasteboard  the  size  of  a  slip,  a  circle  in 
black  ink,  and  use  it  as  a  guide  to  the  brush  with  which 
you  make  the  ring  after  the  slip  is  laid  on  the  paste- 
board. Of  course  the  hand  cannot  be  as  steady  as  a 
flat  disk  rapidly  rotating  on  a  central  pivot,  and  the  cir- 
cles will  not  be  as  perfect,  but  they  will  be  practically 
as  useful.  To  get  the  inked  circle  in  the  centre  of  the 
paper,  draw  a  lead-pencil  line  diagonally  across  it  from 
each  upper  corner  to  the  opposite  lower  one,  and  use  the 
point  at  which  the  two  lines  cross  each  other  as  the  cen- 
tre of  the  circle.  The  glass  slip  can  be  kept  in  better 
position,  and  the  whole  can  be  turned  about,  if  the  paste- 


32  MICROSCOPY  FOR  BEGINNERS. 

board  is  fastened  to  a  strip  of  wood,  and  a  small  pin  is 
driven  into  each  corner.  "When  the  ring  is  made,  put 
the  slip  in  a  warm  place  until  the  cement  is  hard,  or 
hold  it  over  the  lamp  flame  for  a  few  moments  at  a 
time,  taking  care  not  to  allow  the  shellac  to  boil,  or  the 
bubbles  will  never  disappear  and  the  ring  will  be  weak- 
ened. These  lamp-dried  rings  are  hard  as  soon  as  cold, 
and  they  adhere  so  firmly  that  they  can  only  be  scraped 
off  with  a  knife  and  hard  work.  They  have  the  further 
advantage  of  being  rapidly  made. 

A  deeper  and  perhaps  a  somewhat  neater  cell  can  be 
formed  from  paper.  Cut  a  circular  disk,  of  the  diameter 
of  the  ring  required,  from  porous  paper  as  thick  as  the 
depth  of  the  desired  cell,  and  from  the  centre  cut  out  a 
smaller  disk,  leaving  a  ring  with  a  narrow  rim.  Soak  this 
ring  in  thin  shellac  cement  until  its  pores  are  filled  with 
the  liquid,  and  hang  it  on  a  pin  in  a  warm  place  to  dry. 
Several  can  be  prepared  at  once,  and  can  be  of  different 
sizes  and  thickness.  They  are  fastened  to  the  slip  by 
touching  one  side  with  a  little  shellac  and  pressing  the 
glass  on  it  and  allowing  it  to  dry,  or  by  gently  heating 
the  slip  and  ring  over  the  lamp.  It  is  a  good  thing  to 
prepare  several  slips  at  one  time,  so  as  to  have  them 
ready  for  an  emergency,  as,  for  instance,  after  an  excel- 
lent gathering  of  microscopical  material  has  been  made, 
and  the  student  is  so  anxious  to  see  what  he  has  that  he 
cannot  take  time  to  clean  the  slide  and  cover  after  a 
hasty  glance  for  rarities,  but  must  have  another  ready 
at  a  moment's  notice. 


THE   MICROSCOPE  AND   ITS  PARTS.  33 

To  permanently  mount  dry  objects,  such  as  pollen, 
seeds,  scales  from  insect  wings,  and  other  things  suita- 
ble for  this  method  of  preservation,  arrange  the  specimen 
in  the  cell,  place  the  cover  over  it — preferably  a  circle  in 
this  case,  the  diameter  of  the  cell  being  a  little  greater 
than  that  of  the  cover — so  that  the  cement  shall  project 
a  short  distance  beyond  the  edges  of  the  thin  glass,  and 
with  a  camel's-hair  brush  paint  a  thin  layer  of  shellac 
over  the  place  where  the  cover  and  ring  meet.  There 
should  be  but  little  cement  on  the  brush  for  the  first 
coat,  because  if  too  much  is  used,  or  it  is  too  thin,  it 
will  probably  run  into  the  cell  by  capillary  attraction 
and  spoil  the  object.  This  is  one  great  trouble  in  all 
microscopical  mounting.  But  after  the  first  coat  is  dry, 
another  is  to  be  added,  and  repeated  until  the  cover 
is  firmly  fastened  to  the  ring.  "Brown's  Rubber  Ce- 
ment," for  sale  by  the  dealers,  is  useful  for  this  pur- 
pose, as  it  is  very  fluid,  dries  with  great  rapidity,  and 
has  little  tendency  to  "  run  under." 

The  cell  having  been  made,  the  object  is  to  be  placed 
within  it  in  a  drop  of  water,  the  thin  cover  dropped 
over  it,  and  the  preparation  will  then  be  ready  for  ex- 
amination. But  how  is  this  minute,  generally  invisible 
object  to  be  got  into  the  cell  ?  A  glass  tube  about  one- 
tenth  inch  in  inside  diameter,  and  as  long  as  may  be 
convenient,  several  needles  in  wooden  handles,  and  a 
camel's-hair  brush,  with  a  small  smooth  stick  thrust  into 
the  quill,  will  be  needed. 

The  needles  are  used  for  spreading  any  small  mass 


34  MICROSCOPY  FOR  BEGINNERS. 

evenly  over  the  cell,  and  in  disentangling  and  arranging 
the  parts  of  any  comparatively  large  object,  as  well  as 
for  lifting  the  thin  cover  from  the  cell  so  that  it  can  be 
easily  seized  by  the  fingers,  or  for  tilting  it  up  in  the 
box,  where  the  thin  squares  should  always  be  kept. 
Fresh-water  Algae  (Chapter  III.),  for  instance,  found  so 
abundantly  in  almost  all  still  water,  where  they  often 
form  delicate  green  clouds,  or  thread-like  streamers 
adhering  to  other  plants,  dead  leaves,  or  waterlogged 
sticks,  are  almost  sure  to  be  transferred  to  the  slip  in  a 
heaped  up  and  tangled  mass,  which  only  two  needles 
with  gently  persuasive  movements  can  straighten  out 
for  microscopic  study.  If  an  attempt  is  made  to  exam- 
ine such  a  confused  heap,  the  thin  cover  cannot  be 
forced  to  lie  flat  without  crushing  the  delicate  speci- 
mens, and  if  the  cover  is  tilted  the  objective  cannot  be 
properly  focussed.  To  make  these  useful  tools,  with 
pliers  thrust  fine  needles  head  first  into  parlor-matches, 
after  the  phosphorous  ends  have  been  cut  off.  These 
round  sticks  make  handles  convenient  in  length  and 
pleasant  to  use.  It  is  well  to  have  half  a  dozen  or  more 
of  these  needle-bearing  matches  lying  where  they  can 
be  picked  up  whenever  wanted.  If  the  student  desires 
to  dissect  insects,  nothing  can  be  so  useful  for  cutting 
and  tearing  minute  parts  and  for  separating  delicate  tis- 
sues or  organs  as  fine  needles.  !N~o  knives  have  been 
made  to  equal  them  for  this  purpose. 

The  glass  tube  is  the  "dipping-tube."     It  is  really 
one  of  the  most  important  little  pieces  of  apparatus  that 


THE   MICROSCOPE  AND   ITS  PARTS.  35 

the  microscopist  can  have  on  his  table,  if  he  intends  to 
study  aquatic  life.  "With  it  he  can  pick  up  any  small 
object  that  may  be  visible  in  the  water,  transfer  any  se- 
lected matters  to  the  slip,  or  make  the  dip  that  is  made 
by  faith,  with  the  assurance  that  although  the  tube  may 
seem  to  be  filled  with  water  only,  it  will  be  pretty  sure 
to  have  captured  something  interesting,  novel,  or  beau- 
tiful. He  can  fill  the  tube  with  water,  and  allow  it  to 
escape  in  a  miniature  torrent,  or  drop  by  drop,  or  he 
can  allow  a  drop  to  enter  and  a  drop  to  flow  slowly  out 
at  his  will.  Some  workers  prefer  a  tube  with  a  hollow 
rubber  bulb  attached,  by  which  the  water  and  contained 
objects  are  drawn  up  by  the  expanding  ball,  and  forced 
out  by  its  compression.  The  writer  is  prejudiced  in  favor 
of  the  simple  tube,  as  it  is  less  complicated,  more  easily 
cleansed,  and  its  contents  are  more  completely  under 
control.  To  use  it,  place  the  tip  of  the  forefinger  firm- 
ly over  one  end,  and  dip  the  other  into  the  water  above 
and  near  to  the  object  desired ;  lift  up  the  finger,  and  the 
water  will  rush  in  until  it  is  level  with  that  on  the  out- 
side ;  close  the  upper  end  again,  remove  the  tube,  and 
the  water  will  remain  in  it  as  long  as  the  finger  stops 
the  upper  opening ;  remove  the  finger  and  the  water 
will  at  once  flow  out.  By  the  proper  regulation  of  the 
pressure  and  movements  of  the  finger,  the  water  can  be 
made  to  escape  drop  by  drop  or  in  a  sudden  rush.  In 
this  way  any  small  aquatic  object  can  be  easily  trans- 
ferred to  the  slip,  and  as  readily  washed  off  by  a  sudden 
outward  flow  from  a  full  tube. 
3 


36  MICROSCOPY  FOR  BEGINNERS. 

Until  recently  I  supposed  this  little  affair  was  com- 
mon property,  and  that  the  principle  on  which  it  acts 
was  understood  by  everybody.  But  when  I  called  on 
a  gentleman,  a  member  of  a  scientific  society,  to  obtain 
some  water  in  which  certain  plants  were  growing,  he  ex- 
pressed surprise  at  the  performance,  and  called  his  wife 
to  witness  a  new  and  curious  method  of  taking  up  wa- 
ter with  nothing  but  a  glass  tube  and  a  finger.  His  as- 
tonishment was  amusing ;  but  how  much  more  so  was 
that  of  a  druggist  who  had  a  teaspoonful  of  deposit  at 
the  bottom  of  a  conical  glass  vessel  with  a  quart  of  wa- 
ter above  it,  and  who,  after  running  about  for  bottles 
and  jars  to  hold  this  water,  which  he  thought  must  be 
poured  off,  returned  to  find  the  deposit  removed,  and 
in  a  small  phial  in  my  pocket,  the  quart  of  water  re- 
maining undisturbed.  "  Why,"  he  said,  "  that  is  strange. 
I  never  saw  the  like  before.  How  did  you  do  it  ?" 
-  It  is  often  convenient  to  have  several  dipping-tubes, 
some  straight,  others  drawn  out  to  a  point,  and  some 
curved  so  as  to  be  readily  directed  into  a  narrow  corner. 
A  glass  tube  is  easily  pulled  out  to  a  fine  extremity, 
or  variously  curved  when  softened  in  an  alcohol  flame. 
But  a  spirit-lamp  may  not  always  be  within  reach,  and 
is  not  necessary,  for  the  student  can  make  a  Bnnsen 
burner  almost  without  cost,  and  use  it  successfully  if 
his  home  is  supplied  with  illuminating  gas.  Prof.  Aus- 
tin C.  Apgar,  in  Science  News  and  Boston  Journal  of 
Chemistry,  has,  under  the  title  "  A  Bunsen  burner  for 
two  cents,"  recently  described  a  simple  piece  of  appara- 


THE  MICROSCOPE  AND  ITS  PARTS.  37 

tus  that  is  a  boon  to  any  one  desiring  to  do  a  little  ama- 
teur glass-blowing.  A  strip  of  tin  about  six  indies  long 
and  two  wide  is  rolled,  without  solder  or  fastening  of 
any  kind,  into  a  tube  about  half  an  inch  in  diameter, 
after  two  holes,  each  about  one-fourth  inch  in  diameter, 
have  been  punched  so  that  they  shall  be  on  opposite 
sides  of  the  tube,  and  high  enough  to  be  a  short  dis- 
tance above  the  tip  of  the  gas-burner.  This  simple  ar- 
rangement is  forced  over  an  ordinary  burner,  so  that  the 
holes  are  just  above  the  tip,  the  spring  of  the  tin  hold- 
ing it  in  place;  the  gas  is  lighted  at  the  upper  end, 
where  it  burns  without  smoke  and  gives  a  strong  heat, 
the  flame  being  easily  regulated,  and,  with  ordinary  care, 
not  flashing  into  the  tube.  It  is  entirely  successful. 

Evaporation  of  the  water  will  take  place  from  be- 
neath the  thin  cover,  sometimes  quite  rapidly,  and  the 
observer  will  at  first  be  surprised  at  the  way  in  which 
his  objects  will  be  swept  out  of  the  field  before  an  ad- 
vancing wave  that  leaves  the  glass  nearly  dry  behind  it. 
The  water  in  the  cell  is  drying  up,  and  a  fresh  supply 
must  be  added  if  the  objects  are  not  to  be  entirely  lost. 
Here  is  another  advantage  in  using  square  covers  on  cir- 
cular cells.  The  four  corners  project  beyond  the  cement 
ring,  and  by  applying  the  camel's-hair  brush,  wet  with 
water,  to  the  slide  beneath  any  one  of  these  projections, 
the  drop  will  run  in  and  fill  the  cell  by  capillary  attrac- 
tion. This  supply  is  much  more  easily  added  than  if 
circular  covers  are  used,  and  after  a  little  experience  the 
fresh  drops  can  be  applied  while  the  eye  is  at  the  eye- 


38  MICROSCOPY  FOR  BEGINNERS. 

piece,  the  hand  alone  guiding  the  wet  brush,  and  the 
eye  taking  note  of  the  rush  of  the  incoming  wave  and 
the  result.  The  student  will  soon  become  such  an  adept 
that  he  will  be  able  to  add  so  small  a  supply  at  each 
touch  of  the  wet  brush  that  the  movement  of  the  cap- 
illary wave  will  not  be  strong  enough  to  float  the  ob- 
ject out  of  the  field. 

But  it  often  happens  that  a  certain  specimen  is  to  be 
studied  for  a  long  time,  a  whole  evening,  for  instance, 
and  to  be  continually  supplying  the  loss  by  evaporation 
is  not  convenient — the  student  often  becoming  so  ab- 
sorbed that  he  forgets  this  one  of  nature's  laws  until  he 
suffers  the  penalty,  and  probably  loses  his  object.  At 
such  a  time  an  arrangement  is  wanted  for  supplying 
fresh  water  continuously  and  without  demanding  much 
attention,  and  such  a  contrivance  is  easily  made.  With 
a  triangular  file  cut  one  of  the  smallest  homoeopathic 
phials  in  two,  throw  away  the  upper  half,  and  cement 
the  lower  to  a  little  oblong  or  square  piece  of  ordinary 
glass  or  broken  slip.  Attach  this  to  the  slide  by  a  drop 
of  glycerine,  taking  care  not  to  use  too  much,  or  the 
square  will  glide  out  of  place  when  inclined.  Fill  the 
bottle  with  water,  coil  into  it  one  end  of  a  doubled, 
loosely  twisted  thread  of  sewing-cotton,  and  place  the 
other  end  in  contact  with  one  side  of  the  cover,  as  shown 
in  Fig.  3.  The  water  will  pass  down  the  thread  to  one 
edge  of  the  cell,  where  it  will  flow  under  as  it  evapo- 
rates from  the  other  three  sides.  This  usually  works 
well,  the  secret  of  success  being  to  have  the  reservoir 


THE   MICROSCOPE  AND   ITS  PARTS. 


Fig.  3.— A  Growing-slide. 


not  more  than  three-quarters  of  an  inch  from  the  cell, 
to  keep  it  always  full  of  water,  and  to  have  the  doubled 
thread  applied  closely 
against  the  cover.  If 
the  water  supply  is 
too  great,  and  the  cell 
is  disposed  to  over- 
flow, shorten  the  end 
of  the  thread  against 
the  cover ;  if  not  enough,  lengthen  it,  and  do  not  allow 
the  thread  to  touch  the  slide  in  its  course  from  the 
reservoir  to  the  cell. 

Again,  the  observer  frequently  wants  to  make  a  grow- 
ing-cell of  the  slide  on  which  he  may  accidentally  have 
placed  a  desirable  or  beautiful  object ;  that  is,  he  desires 
to  preserve  the  specimen  for  several  days  in  the  cell 
without  disturbing  it,  and  so  taking  the  risk  of  losing 
the  invisible  thing.  He  may  also  wish  to  watch  its 
growth  and  development.  A  reservoir  for  'a  water  sup- 
ply is  necessary ;  an  "  individual "  butter-dish  makes  a 
good  one.  Place  the  slide  across  the  dish,  apply  a  dou- 
bled thread  of  sewing-cotton  along  one  side  of  the  square 
cover,  so  that  each  end  shall  hang  down  into  the  dish, 
and  fill  the  latter  with  water,  which  will  then  pass  up 
and  along  the  thread,  and  keep  the  cell  full  for  as  long 
as  may  be  desired.  The  only  objection  to  this  little  af- 
fair is  that,  after  a  few  days'  use,  the  salts  in  the  water 
will  crystallize  on  the  cover,  and  so  cut  off  part  of  the 
oxygen  supply.  But  no  growing-cell  is  free  from  some 


40  MICROSCOPY  FOR  BEGIXXERS. 

objectionable  features ;  none  can  quite  imitate  the  natu- 
ral conditions,  and  the  animal  or  plant  dies  before  long, 
either  falling  to  pieces  or  becoming  buried  beneath  a 
mass  of  fungi.  This  one  will  supply  an  abundance  of 
water,  if  the  water  in  the  dish  is  always  kept  in  contact 
with  the  lower  surface  of  the  slide.  This,  and  the  ab- 
solute contact  of  the  thread  with  the  edge  of  the  cover, 
are  the  only  things  whose  absence  will  result  in  defeat. 
As  the  reader  already  understands,  the  object  must 
never  be  examined  in  water  without  being  covered  by 
either  a  thin  glass  circle  or  square ;  the  importance  of 
this  little  piece  of  glass  must  not  be  forgotten.  But 
very  often,  in  lowering  it  over  the  wet  specimen,  small 
bubbles  of  air  will  be  caught  and  not  noticed  until  mag- 
nified, when,  if  seen  for  the  first  time,  they  appear  won- 
derful, if  not  startling.  Some  strange  statements  have 
been  made,  and  discoveries  announced  whose  only  foun- 
dation has  been  minute  air-bubbles  that  the  observer 
did  not  recognize.  A  man  once  described  a  marvellous 
something  that  he  had  found  in  a  cancer, 
which  turned  out  to  be  a  magnified  air- 
bubble.  These  little  air-drops  always 
play  an  amusing  part  at  the  beginning 
of  the  microscopist's  career.  In  Fig.  4 
are  shown  several  of  different  sizes.  Let 
Fig. 4.— Air-bubbies.  the  student  examine  a  drop  of  saliva  or 
of  soapsuds,  and  he  will  in  future  be  able 
to  recognize  the  troublesome  things.  Pictures  or  words 
cannot  convey  so  true  an  idea  of  their  appearance  as  a 


THE  MICROSCOPE  AND  ITS  PARTS.  41 

single  sight  of  the  bubbles  themselves.  At  times  they 
become  entangled  in  the  parts  of  an  object  in  such  num- 
bers as  to  interfere  with  its  examination.  In  these  cases 
nothing  can  be  done  except  to  lift  the  cover  on  the 
point  of  the  needle,  and  slowly  lower  it,  or  remove  it 
entirely,  add  more  water,  and  reapply  it  carefully.  In 
appearance  the  bubbles  are  usually  circular,  with  a  broad 
black  border  which  varies  in  width  and  depth  of  color 
as  the  objective  is  raised  or  lowered.  Near  the  margin 
is  a  bright  ring,  and  in  the  centre  a  bright  spot.  They 
often  float  about,  and  this  movement  adds  much  to  the 
wonder  with  which  the  beginner  usually  regards  them. 

If  the  student  will  have  a  note-book  in  which  to  jot 
down  his  observations,  or  to  keep  a  list  of  the  objects 
examined,  it  will  not  only  aid  him  in  forming  habits  of 
accurate  observation,  but  will  be  of  great  interest  when 
he  has  become  an  accomplished  microscopist.  The  en- 
try may  be  very  simple,  and  may  be  made  to  serve  as  a 
memorandum  of  items  to  refresh  the  memory.  Here  is 
an  example  from  a  boy's  note-book:  "June  15,  1884 — 
Came  across  a  pool  near  the  toll-gate  with  the  water 
colored  green,  and  found  the  color  was  caused  by  a  great 
quantity  of  Volvox — small  green  globes  rolling  about  in 
the  water.  Volvox  is  said  to  be  a  plant.  Wonder  if  it 
is.  What  are  the  darker  balls  inside  of  some  of  them  ?" 
He  answered  all  these  queries  later  in  his  experience. 

If  you  can  draw  the  microscopic  objects  that  interest 
you  most,  although  the  sketches  may  not  be  quite  artis- 
tic they  will  help  you  to  remember,  and  a  collection 


42  MICROSCOPY  FOR  BEGINNERS. 

of  such  drawings  will  be  as  interesting  and  valuable  as 
the  note-book.  In  talking  to  friends  about  microscopic 
matters,  a  single  rough  drawing  will  do  more  to  help 
them  understand  than  many  words.  And  if  you  can 
look  at  the  object  and  make  the  sketch,  you  will  like  it 
better  and  do  yourself  more  good  than  if  you  bought 
and  used  the  drawing  apparatus  called  a  camera  lucida, 
for  sale  by  the  dealers.  This  camera  lucida  is  a  glass 
prism,  so  arranged  that  when  it  is  put  over  the  eye-piece, 
and  the  microscope  is  placed  in  a  horizontal  or  inclined 
position,  the  magnified  image  seems  to  be  reflected  down 
on  a  sheet  of  paper  spread  on  the  table  just  under  the 
camera,  but  of  course  with  a  space  of  several  inches  be- 
tween them.  By  placing  the  eye  in  the  proper  position, 
and  looking  down  towards  the  table  through  the  edge  of 
the  prism,  the  image  and  the  pencil-point  can  both  be 
seen  at  once  and  the  outlines  traced.  It  is  a  rather  ex- 
pensive apparatus,  and  difficult  to  use  without  a  good 
deal  of  practice,  but  if  you  want  a 
simple  arrangement  that  you  can 
make,  try  the  one  shown  in  Fig.  5. 

From  a  piece  of  thin  sheet  brass 
or  tin,  cut  with  scissors  a  strip  half 
an  inch  wide  and  long  enough  for 
B.  —  Reaector  for     one  end  to  pass  around  the  upper 

Drawing  the  Magni-  . 

fled  object.  part  oi  the  eye-piece,  and  the  other 

to  be  bent  into  a  handle  like  a  small 

hollow  square.     Cut  another  strip  about  one  inch  long 

and  one-fourth  wide,  and  double  it  lengthwise  so  that  it 


THE  MICROSCOPE   AND   ITS  PARTS.  43 

will  still  be  an  inch  long,  but  one-eighth  of  an  inch 
broad.  Take  one  of  the  small  brass  hinges  to  be  had  for 
a  cent,  solder  one  end  to  the  hollow  handle  and  the  other 
to  the  narrow  doubled  strip;  into  this  narrow  piece  place 
a  thin  glass  square,  the  thinner  the  better,  and  the  instru- 
ment is  done.  To  use  it,  turn  the  microscope  horizontal, 
have  a  faint  light  on  the  object  and  a  strong  one  on  the 
paper,  bend  the  strip  of  brass  around  the  upper  part  of 
the  eye-piece  so  it  will  not  slip,  the  hollow  handle  and 
hinge  being  directed  towards  the  table,  and  move  the 
hinge  until  the  thin  cover  is  placed  obliquely  in  front 
of  the  eye-glass  of  the  eye-piece.  Look  down  through 
the  glass  square  towards  the  paper  on  the  table,  and  the 
image  of  the  object  on  the  stage  will  seem  to  be  thrown 
on  the  white  surface,  where  it  can  be  traced  with  a  pen- 
cil. The  image  is  really  reflected  from  the  surface  of 
the  thin  square,  and  the  pencil  is  seen  through  it,  but  the 
eye  unconsciously  combines  them  so  that  both  are  seen 
together.  The  secret  of  success  here  is  a  faint  light  on 
the  object,  a  strong  one  on  the  paper,  and  a  thin  glass 
square.  A  long,  sharp  pencil-point  is  also  an  advantage. 
A  micrometer  is  for  measuring  objects  under  the  mi- 
croscope. It  is  made  by  ruling  a  number  of  short  lines 
on  glass,  the  spaces  between  the  lines  varying  from  j^-g- 
to  1016&-  inch  or  less.  Micrometers  are  said  to  have  been 
ruled  with  one  million  lines  to  the  inch,  but  no  human 
eye  using  the  best  and  highest  power  objectives  has  ever 
seen  them.  All  micrometers  are  ruled  by  a  machine 

made  for  the  purpose. 
3* 


44  MICROSCOPY  FOR  BEGINNERS. 

The  beginner  will  not  need  one,  but  ho  may  desire  to 
know  how  to  use  it.  Place  the  micrometer  on  the 
stage,  turn  the  microscope  horizontal  with  the  reflector 
referred  to  above,  fitted  to  the  eye -piece.  "With  the 
low-power  objective  focus  the  lines  that  are  yfg-  inch 
apart,  and  draw  them  on  the  paper.  Do  the  same  with 
every  objective,  drawing  the  y^  inch  spaces  with  the 
£  or  £  lenses.  These  drawings  will  form  the  scale  for 
measuring  the  drawings  of  the  magnified  objects.  Thus, 
if  the  magnified  object,  when  drawn,  occupies  two  spaces 
of  your  paper  scale  made  from  the  y^-g-  inch  micrometer 
spaces,  the  object  will  measureyl-j,  or  -^  inch  in  length ; 
if  five  spaces  of  your  scale,  then  it  will  measure  yjj-^,  or 
•g1^  inch  long ;  if  only  one-half  a  space  of  your  scale, 
then  it  will  measure  one-half  of  y^-  of  an  inch  ;  if  one- 
fourth  of  your  scale  space,  then  its  actual  length  will  be 
•j-J-5-  inch.  If  the  £  or  -^  objective  is  used  in  making 
your  scale  from  the  10*00  inch  micrometer  spaces,  then 
each  division  on  the  paper  will  represent  10*00  inch,  and 
if  the  drawing  of  the  object  measures  two  of  these 
spaces  on  your  scale,  the  real  length  of  the  object  will 
be  y^j-  inch,  or  Tfj-.  It  is  perceived  that  the  stage 
micrometer  cannot  be  used  for  measuring  objects  direct- 
ly, but  only  by  applying  the  drawing  of  the  magnified 
micrometer  spaces  to  the  drawing  of  the  magnified  ob- 
ject. 

The  micrometer  can  also  be  used  to  ascertain  the 
power  of  the  microscope.  If  each  of  the  y^-g-  inch  spaces 
measures,  when  drawn  on  the  paper,  T^  inch,  that  com- 


THE   MICROSCOPE   AND   ITS  PARTS.  45 

bination  of  eye-piece  and  objective  will  have  a  magnify- 
ing power  of  ten  diameters ;  if  each  y^-  inch  microm- 
eter space  measures  -^  inch,  the  power  will  be  forty 
diameters ;  each,  therefore,  corresponds  to  ten  times.  If 
the  YoVtf  mch  micrometer  spaces  measure,  when  drawn, 
Y1^  inch,  then  each  tenth  corresponds  to  a  power  of  one 
hundred  times ;  therefore,  if  the  ^-^  inch  spaces,  when 
magnified,  measure  ten-tenths,  the  power  of  that  eye- 
piece and  objective  is  of  course  one  thousand  diameters, 
or  ten  times  one  hundred ;  if  five-tenths,  then  five  times 
one  hundred. 

The  owner  of  a  microscope  should  never  take  a  walk 
in  the  country  without  one  or  two  wide-mouthed  bot- 
tles in  his  pocket.  Empty  morphia  bottles,  to  be  had 
of  any  druggist,  are  convenient  for  small  collections ; 
for  greater  quantities  an  empty  quinine  bottle,  and  for 
still  larger  gatherings  of  aquatic  plants  the  ordinary 
glass  fruit-jar  is  admirable  if  a  string  is  added  for  a  han- 
dle. No  bottle  should  be  entirely  filled  and  corked,  or 
all  animal  life  will  be  animal  death  before  the  micro- 
scope is  reached.  Leave  a  large  space  for  air  between 
the  cork  and  the  water. 

Those  desiring  information  as  to  the  optical  construc- 
tion of  the  compound  microscope,  the  uses  of  the  numer- 
ous pieces  of  apparatus  often  used  for  advanced  work, 
and  about  the  methods  of  permanently  mounting  micro- 
scopic objects,  may  advantageously  consult  the  follow- 
ing publications : 


46  MICROSCOPY  FOR   BEGINNERS. 

''How  to  Use  the  Microscope."  16mo.  By  John  Phinn.  New 
York.  "  How  to  See  with  the  Microscope."  12mo.  ByDr.J.  E. 
Smith.  Chicago.  "How  to  Work  with  the  Microscope."  8vo. 
By  Dr.  Lionel  S.  Beale.  London.  "The  Microscope."  Small  4to 
By  Dr.  W.  B.  Carpenter.  London.  "  The  Micrographic  Diction  - 
ary."  8vo.  London.  "Manual  of  Microscopic  Mounting."  8vo. 
By  John  N.  Martin.  Philadelphia.  "  The  Preparation  and  Mount- 
ing of  Microscopic  Objects."  16mo.  By  Thomas  Davies.  London. 
The  American  Monthly  Microscopical  Journal.  Washington,  D.  C. 
The  Microscope:  an  Illustrated  Monthly  Journal.  Ann  Arbor, 
Mich. 


AQUATIC  PLANTS  USEFUL  TO  THE  MICROSCOPIST. 


CHAPTER  II. 

COMMON  AQUATIC   PLANTS    USEFUL    TO   THE   MICROSCOPIST. 

Ranunculus.  — Nymphaea.  — Myriophyllum.  — Utricularia.  — Cerato- 
phy  Hum. — Lernna.  — Anacbaris.  —  Vallisneria. — Sphagnum.  — Ric- 
cia. 

THERE  are  several  common  plants  floating  freely  in 
the  water,  or  more  or  less  firmly  rooted  in  the  mud  at 
the  bottom  of  shallow  ponds  and  slowly  flowing  streams, 
that  are  important  to  the  student  of  microscopic  aquatic 
life.  This  may  be  either  through  their  own  interesting 
or  peculiar  structure,  or  on  account  of  the  minute  plants 
and  animals  living  among  their  tangled  leaves  or  at- 
tached to  the  stem  and  other  parts,  these  entangled  ob- 
jects being,  therefore,  more  easily  and  surely  captured 
by  transferring  the  larger  visible  growths  to  a  small 
vessel  of  water  than  in  any  other  way.  Most  of  these 
aquatic  plants  have  their  leaves  divided  into  fine,  thread- 
like leaflets.  They  have  "  dissected  leaves,"  as  the  bot- 
anist names  them,  and  they  become  the  favorite  resorts 
of  invisible  animals  which  attach  themselves  to  the  nar- 
row divisions,  and  feed  on  the  free-swimming  kinds  that 
also  find  the  same  places  attractive.  So,  if  the  student 
desires  to  gather  microscopic  material,  let  him  find  any 
of  the  following  plants  and  he  will  be  quite  sure  to  get 
what  he  wants.  But  he  must  remember  that  by  lifting 


48  MICROSCOPY  FOR  BEGINNERS. 

them  out  of  the  water  very  many  of  the  creatures  he 
most  desires  will  be  washed  away.  The  plants  should 
be  slowly  and  carefully  drawn  to  the  shore,  and  lifted 
out  in  a  tin  dipper  and  poured  into  a  wide -mouthed 
bottle.  The  small  tin  dipper  will  prove  a  very  conven- 
ient implement  for  all  kinds  of  microscopical  collecting, 
as  a  handle  of  any  length  can  be  made  by  thrusting  a 
stick  into  the  hollow  handle  of  the  dipper.  If  the  lat- 
ter, however,  is  not  accessible,  the  plants  may  be  gently 
pushed  into  the  bottle,  after  it  has  been  partly  sunk  so 
that  it  lies  parallel  with  the  surface  of  the  water. 

Many  of  our  commonest  aquatic  plants  have  no  com- 
mon English  names,  probably  because  most  of  them 
bear  the  smallest  and  least  showy  flowers  of  all  bloom- 
ing plants,  and  therefore  do  not  attract  the  attention  of 
the  ordinary  observer.  In  referring  to  them,  the  begin- 
ner must  use  the  scientific  names,  or  learn  the  meaning 
of  the  Latin  words  and  use  the  translation,  usually  with 
awkward  results.  It  sounds  better  and  is  quite  as  easy 
to  speak  of  Myriophyllum  as  of  the  "  thousand-leaved 
plant,"  which  the  word  means.  Many  plants  might  be 
styled  thousand-leaved;  another  common  aquatic  one, 
for  instance,  which  often  grows  in  the  same  pond  with 
Myriophyllum,  the  Ceratophyllum,  called  "hornwort" 
because  the  leaves  are  rather  stiff  and  horny ;  and  Lem- 
na,  as  a  word,  is  prettier  and  more  appropriate  than 
"duckmeat,"  an  ugly  term  and  meaningless,  because 
ducks  have  nothing  to  do  with  the  plant. 

If  the  reader  is  not  already  familiar  with  the  appear- 


AQUATIC  PLANTS  USEFUL  TO  THE  MICROSCOriST.      49 


ance  of  the  following  forms,  he  need  have  no  trouble  in 
learning  their  names,  although  he  may  not  have  studied 
botany ;  he  has  only  to  compare  the  leaves  with  the 
figures  in  this  chapter.  It  is,  of  course,  understood  that 
there  are  many  aquatic  plants  not  here  referred  to,  only 
those  being  included  in  this  list  which  afford  the  most 
certain  supply  of  microscopic  life.  The  leaves  of  many 
water-plants  fall  against  the  stem  and  cling  together 
when  lifted  into  the  air ;  but  if  the  student  will  place  a 
small  part  of  the  plant  in  a  saucer  ("individual"  butter 
dishes  are  good  for  this  purpose),  he  can  float  them  out 
against  the  white  surface  and  so  compare  them  with  the 
figures. 

RANUNCULUS  AQUATILIS  (Fig.  6). 

A  part  of  the  stem  and  a  single  leaf  of  this  plant  are 
shown  about  natural  size  in  the  figure  (Fig.  6).  It  is 
quite  common  in  ponds  and 
slowly  flowing  streams:  The 
leaves  are  dissected  into  fine, 
rather  stiff  and  hair -like  parts, 
to  which  many  minute  animals, 
such  as  Rotifers  (Chapter  VIIL), 
Vorticellas  (Chapter  V.),  and 
Stentors  (Chapter  V.)  are  fond 
of  attaching  themselves.  The 
leaves  are  placed  above  each 
other  on  opposite  sides  of 
the  rather  brittle  stem,  and  usually  quite  wide  apart. 


Fig.  6.— Leaf  of  Ranunculus 
nqndtilis. 


50  MICROSCOPY  FOR  BEGINNERS. 

The  whole  plant  is  under  water  except  at  flowering- 
time,  when  it  raises  a  delicate  stalk  above  the  surface, 
and  blooms  with  a  single  white  flower  closely  resem- 
bling the  common  yellow  "  buttercup  "  of  the  fields. 

NYMPHJEA   ODORATA  (Wmra  WATER-LILY,  Fig.  7). 

Every  one  is  familiar  with  this  beautiful  flower,  that 
"  marvel  of  bloom  and  grace,"  and  the  large,  almost  cir- 
cular, floating  leaves.  It  is  to  the  under-surface  of  the 
latter  that  the  microscopist  often  goes  for  several  forms 
of  case-building  Rotifers,  with  the  certainty  of  always 
finding  them,  together  with  many  and  various  kinds  of 
minute  animal  life.  It  is  also  an  excellent  place  to 
search  for  worms.  You  will  usually  find  these  creat- 
ures if  the  surface  is  gently  scraped  and  the  dark  mass 
obtained  is  examined  in  water. 

But  if  the  scented  blossom  is  beautiful  to  the  ordi- 
nary observer,  the  interior  of  the  flower-stems  and  leaf- 
stalks lias  charms  known  only  to  the  microscopist. 
Gut  a  thin  slice  from  either  of 
those  parts  and  examine  it.  The 
sides  of  the  wide  openings  made 
by  cutting  across  the  internal 
tubes  are  studded  with  crystal- 
line stars  (Fig.  7).  Three-point- 
ed, four  and  five  pointed,  they 
Fig .  r.-pedancie  of  Nymphsea  sparkle  there  like  diamonds,  yet 

odorata ;  transverse  section. 

they  were  formed  in  darkness, 
and  in   darkness   act   their   part    in    the   life   of   the 


AQUATIC  PLANTS  USEFUL   TO   THE   MICROSCOPIST.      51 

plant.  What  that  part  is  we  can  only  guess.  Botan- 
ists call  them  internal  hairs ;  but  they  are  hard,  sharp, 
and  brittle.  They  are  hollow,  too,  and  their  surface  is 
roughened  by  minute  elevations,  as  though  fairy  fingers 
had  sprinkled  them  with  crystal  grains.  I  never  see  a 
white  water-lily  without  in  imagination  seeing  those 
long  stalks  rising  out  of  the  black  mud  up  through  the 
dark  water,  with  their  entire  length  illuminated  by  the 
sparkling  of  these  internal  star-like  gems.  The  whole 
plant  contains  them,  even  the  root.  The  common  "  spat- 
ter-dock " — hideous  name ! — the  Nuphar,  also  conceals 
similar  stellate  hairs  within  its  stems,  but  they  are  there 
larger  and  coarser,  as  becomes  a  coarser  plant.  The 
leaves  of  the  Nuphar,  however,  are  not  a  good  micro- 
scopical hunting-ground,  as  they  usually  stand  high 
above  the  water. 

MYRIOPHYLLUM  (Fig.  8). 

This  is  not  rare  in  shallow  ponds  and  slow  streams ; 
it  even  occurs  in  running  water,  but  there  it  is  not 
worth  gathering,  so  far  as  any  adherent  microscopical 
life  is  concerned.  Indeed,  no  running  water  is  a  good 
locality  for  free-swimming  creatures,  because  the  current 
sweeps  them  away,  and  so  scatters  them  that  it  is  not 
possible  to  make  a  collection.  But  where  Myriophyllum 
grows  it  usually  grows  abundantly.  It  forms  long  green 
streamers,  round  and  thick,  sometimes  more  than  an 
inch  in  diameter  and  several  feet  long,  yet  it  looks  soft 
and  feathery.  The  leaves  are  very  numerous,  and  each 


52 


MICROSCOPY  FOR  BEGINNERS. 


Fig.  8.— Whorl  of  Myriophyllnm 
Leaves. 


set  is  arranged  in  a  circle  around  the  stem ;  they  are  in 
"whorls,"  as  the  botanist  calls  the  arrangement.     One 
such  whorl  is  shown  in  Fig.  8.     Five  dissected  leaves 
are  there  drawn,  but  whorls 
sometimes   occur  with  three 
or  four,  the  number  helping 
to    distinguish    the    species, 
of  "which  there  are  several. 
They  all  resemble  one  anoth- 
er when  in  the  water.     The 
parts    of   the    leaf   are  fine, 
soft,  and  hair-like,  those  near- 
est  the   stem    of  the   plant 
being  the  longest.     They  are 
very  numerous  and  close  to- 
gether, thus  giving  the  floating  streamers  their  pecul- 
iar thick  and  soft  appearance,  and  making  them  an  ex- 
cellent place  for  the  microscopist  to  explore. 

To  compare  with  Fig.  8  a  feathery  plant  which  the 
collector  does  not  know,  select  a  circle  of  leaves,  cut  the 
stem  close  above  and  below  it,  and  after  floating  the 
separated  whorl  in  a  saucer  as  already  directed,  or  spread- 
ing it  out  on  white  paper,  compare  its  leaves  with  those 
figured.  The  leaves  vary  in  size  in  different  parts  of 
the  plant,  the  uppermost  being  smallest  and  youngest, 
the  lower  the  oldest  arid  largest. 

There  is  another  rather  common  aquatic  plant  called 
Proserpindca,  or  "  mermaid- weed,"  which  so  closely  re- 
sembles Myriophyllum  when  in  the  water  that  it  has 


AQUATIC   PLANTS  USEFUL   TO   THE   MICROSCOPIST.      53 


often  been  mistaken  for  it.  To  make  such  an  error  is 
of  no  great  consequence,  unless  it  should  lead  the  ob- 
server to  imagine,  as  it  once  did  the  writer,  that  he  has 
found  a  rare  species  of  Myriophyllum.  Yet  it  is  always 
pleasant,  if  nothing  else,  to  feel  sure,  and  it  is  more  than 
pleasant  to  have  a  reputation  for  accurate  observation. 
Proserpinaca,  however,  is  as  useful  a  trap  as  Myriophyl- 
lum, and  it  can  be  easily  distinguished  because  the  dis- 
sected leaves  are  not  in  an  exact  circle  around  the  stem : 
one  is  on  one  side,  the  next  a  little  further  round  and  a 
little  higher  on  the  stem,  another  still  further  round  and 
nearer  the  first,  but  still  higher.  They  are  what  the  bot- 
anist calls  alternate. 

Either  of  these  plants  is  a  specially  good  place  for 
attached  diatoms  (Chapter  III.). 


UTRICULARIA  (Figs.  9  and  10). 

Of  all  our  water-plants  with  finely  divided 
Utricularia  is  probably  the  most  interesting  in 
and  one  that  can  always  be  recog- 
nized at  a  glance.  It  is  found  in 
long,  somewhat  branching  streamers, 
floating  freely  below  the  surface  or 
very  slightly  rooted.  A  leaf  of  Utri- 
cularia vulgdris,  a  common  species, 
is  shown  somewhat  enlarged  in  Fig. 
9,  with  the  peculiar  hollow  bladders, 
or  "  utricles,"  that  distinguish  it  from 
all  other  plants,  and  give  it  one  of  its 


leaves, 
itself, 


Fig.  9 A  Leaf  of  Utricn- 

laria. 


54  MICROSCOPY  FOR  BEGINNERS. 

scientific  names.  These  utricles  are  almost  always  con- 
spicuous when  the  plant  is  taken  from  the  water,  as 
small,  green,  semi-transparent  particles  attached  to  the 
leaves.  They  are  not  unlike  small  pieces  of  jelly  in 
appearance,  until  examined  with  the  microscope,  when 
their  remarkable  structure  is  seen.  Until  within  a  few 
years  they  were  supposed  to  act  as  air-sacs  to  help  the 
plant  float.  It  was  even  said  that  they  became  filled 
with  air  or  gas  at  flowering-time,  and  so  lifted  the  flow- 
er-stalk and  the  bloom  above  the  water.  This  was  in- 
teresting, but  the  truth  is  more  interesting  and  star- 
tling. The  plant  actually  feeds  on  animals.  These 
bladder-like  bodies  are  the  food-traps,  the  mouths  and 
the  stomachs  of  the  Utricularia. 

Under  the  microscope  they  are  seen  to  be  hollow,  oval 
bodies,  with  a  narrow,  almost  straight  anterior  end,  and 
several  long  bristles  projecting  forward  or  away  from 
the  utricle,  these  bristles  probably  serving  as  a  guide  to  an 
opening  at  their  base.  The  little  animal  swims  or  crawls 
against  a  bristle,  and  naturally  moves  down  it  towards 
the  opening  in  the  utricle,  which  it  finds  closed  by  a 
transparent  colorless  curtain ;  this  it  pushes  aside  and 
passes  on  into  the  trap.  The  curtain-like  valve  is  at- 
tached by  its  upper  and  lateral  margins,  therefore  hang- 
ing before  the  opening  in  the  utricle,  and  swinging  in- 
ward, but  so  arranged  that  it  cannot  be  forced  outward  by 
any  creature  small  enough  to  pass  within.  Indeed,  the 
power  that  the  valve  seems  to  exert  is  somewhat  astonish- 
ing. Small  fish  have  been  found  with  the  tail  or  even  the 


AQUATIC   PLANTS  USEFUL   TO   THE   MICROSCOPIST.      55 

head  inside  tlie  utricle,  and  firmly  held  by  the  pressure 
of  the  valve.  In  these  cases,  however,  it  seems  proba- 
ble that  the  struggles  of  the  dying  fish  may  have  wedged 
it  fast,  rather  than  that  the  valve  has  held  it.  Small 
worms  and  worm-like  larvae  have  been  found  half  in  and 
half  out  of  these  fatal  traps,  for  once  past  the  curtain- 
like  valve  the  little  animal  never  escapes.  ,And  no 
sooner  has  it  entered  than  it  begins  to  show  signs  of 
discomfort ;  if  it  has  a  shell  it  withdraws  its  legs  and 
head  and  closes  the  shell ;  if  a  worm  or  animalcule  it 
speedily  becomes  languid,  its  movements  cease,  and  it 
finally  dies,  as  does  every  creature  that  ventures  into 
Utricularia's  utricles,  which  evidently  contain  something 
more  than  simple  water.  If  these  bladders  are  torn  to 
pieces  under  the  microscope  with  the 
needles,  the  remains  of  many  kinds  of 
minute  creatures  will  be  seen,  the  soft 
parts  of  the  captives  having  been  dissolved 
and  absorbed,  and  gone  to  nourish  the  FitT10  _ 
plant  The  whole  inner  surface  of  the  fid  Process  n-om 

.     ,.        ,    ,        .  Inner  Surface  of 

utricles  is  lined  by  innumerable  colorless  utricle  of  utri- 
four-parted  bodies,  one  of  which  is  shown 
much  magnified  in  Fig.  10.  They  are  distinctly  visible 
only  when  the  utricle  is  torn  to  pieces.  They  are  said  to 
absorb  the  fluid  in  which  the  entrapped  animals  are  dis- 
solved. 

CERATOPHYLLUM  DEMERSUM  (Fig.  11). 

This  is  commoner  and  more  abundant  than  Myrio- 
phyllum,  for  which  it  is  often  mistaken,  although  the 


56  MICROSCOPY  FOR  BEGINNERS. 

two  have  only  a  remote  general  likeness.  The  leaves  of 
Myriophyllum  are  fine  and  soft,  those  of  Ceratophyllum 
rather  coarse  and  stiff.  In  the  latter  they  are  whorled 
with  six  to  eight  in  each  circle,  but  instead  of  being  di- 
vided on  each  side  down  to  the  middle  line  (the  midrib), 
as  in  Myriophyllum,  they  appear 
to  separate  into  two  narrow  parts 
near  the  stem,  while  each  division 
then  often  divides  into  two  other 
parts.  Both  these  arrangements  are 
represented  in  Fig.  11,  where  the 
whorl  is  shown  separated,  as  was 
Fig.  11.— whori  of  Lcaves^of  done  in  Myriophyllum.  The  leaves 
always  bear  several  very  small  but 
visible  spines  on  their  sides,  as  in  the  figure,  and  when 
taken  from  the  water  they  usually  do  not  fall  against 
the  stem. 

The  plant  is  found  in  still,  shallow  places,  growing  in 
thick  masses  and  often  considerably  branched.  It  makes 
an  excellent  retreat  for  certain  Rotifers  and  worms,  but 
the  leaves  are  so  heavy  and  stiff  that  they  are  not  as 
easily  prepared  for  microscopical  examination  as  are 
those  of  Myriophylluin ;  they  often  refuse  to  lie  flat, 
and  thus  tilt  the  cover  glass  and  allow  the  water  to  run 
away.  But  with  neither  of  these  plants  will  the  student 
try  to  place  an  entire  whorl  in  the  cell.  It  is  always 
best  to  clip  off  with  scissors  a  part  of  a  single  leaf,  and 
examine  it  for  whatever  may  be  attached.  Work  with 
the  microscope  is  delicate  work,  and  the  smaller  the  ob- 


AQUATIC  PLANTS  USEFUL  TO  THE  MICROSCOPIST.       57 

jectj  within  certain  limits,  the  better.  Many  beginners 
make  the  mistake  of  trying  to  examine  too  large  a  speci- 
men or  too  much  of  a  mass  at  once. 


LEMNA  POLYRRHfZA  (Fig.  12)  AND  LEMNA  MfNOR  (Fig.  13).- 
DUCKMEAT. 

These  are  small  plants,  very  common,  and  often  so 
abundant  that  the  entire  surface  of  large  ponds  is  cov- 
ered by  them  as  by  a  green  carpet.  The  water  in  such 
cases  is  so  completely  covered  and  concealed  that  the 
observer  is  for  a  moment  tempted  to  step  on  it.  The 
above  two  species  resemble  each  other,  yet  they  differ 
so  widely  that  a  glance  will  distinguish  them.  Each 
consists  of  a  small  green,  more  or  less  oval  leaf  or  frond 
floating  on  the  water,  with  one  or  more  rootlets  hanging 
from  beneath,  but  never  taking  root  in  the 
mud.  Usually  two,  three,  or  four  fronds 
are  attached  together,  so  as  to  form  an  ir- 
regular star.  Lemna  poly  rrhiza,  the  many- 
rooted  one  (Fig.  12),  has  the  largest  fronds, 
is  a  deeper  green,  and,  as  its  specific  name  Fig.  12.— Lemna 
signifies,  has  many  rootlets,  often  a  dozen, 
hanging  in  a  cluster  from  each.  It  can  always  be 
known  by  this  root-cluster  and  by  the  dull  purple  color 
of  the  lower  surface.  It  seems  to  like  the  sun  better 
than  Lemna  minor,  and  is  oftener  found  abundantly  on 
open  ponds,  while  the  latter  appears  to  prefer  ditches 
with  high  banks  and  shade. 

Lemna  minor  (Fig.  13)  has  smaller,  more  oval  and 


58  MICROSCOPY  FOR  BEGINNERS. 

thinner  fronds.     It  is  lighter  green  in  color,  the  lower 
surface  is  never  purplish,  and  it  has  but  one  rootlet  to 
each  frond.     Both  species  have  a  curious  little 
^^      cap  on  the  free  end  of  each  rootlet.    It  is  more 
easily  seen  with  the  naked  eye  on  Lemna  polyr- 
rhiza,  where  it  is  usually  darker  than  the  rest 
of  the  rootlet. 

There  are  several  other  species,  but  they  are 
so  seldom  found  that  they  are  not  included  in 

Xlg.   13.  — 

L6mna  this  list.  They  all  multiply  by  the  growth  of 
young  fronds  from  the  edges  of  the  old  and 
mature.  This  accounts  for  the  clusters  so  commonly 
seen.  They  also  bloom,  but  the  flowers  are  extremely 
small  and  are  rarely  observed.  The  student  will  be  fort- 
unate to  find  specimens  in  blossom.  The  flowers  burst 
out  of  the  margin  of  the  frond,  and  consist  of  only 
those  parts  needed  to  fertilize  and  mature  the  few  small 
seeds. 

The  rootlets  are  valuable  to  the  microscopist,  as  they 
are  favorite  places  for  many  just  such  creatures  as  he 
most  wants.  The  lower  surface  of  the  fronds,  especially 
of  Lemna  polyrrhiza,  should  be  gently  scraped  in  a  drop 
of  water  for  Rotifers  not  often  found  elsewhere.  It  is 
also  much  visited  by  small  worms,  but  not  so  frequently 
as  the  leaves  of  the  white  water-lily. 

ANlCHARIS  CANADENSIS  (Fig.  14). 

This  is  readily  recognized  by  the  arrangement  of  the 
leaves  in  circles,  or  whorls,  of  three  each,  two  of  which 


AQUATIC  PLANTS  USEFUL  TO  THE  MICROSCOPIST.      59 

are  shown  in  Fig.  14.  The  stem  is  brittle,  and  frag- 
ments easily  take  root,  so  that  the  plant  spreads  rapidly. 
Having  been  accidentally  introduced  into 
England,  it  is  said  to  have  grown  so  fast 
that  it  has  choked  up  some  of  the  shallow- 
er streams  and  to  have  become  a  nuisance. 
It  is  abundant  in  this  its  native  country, 
but  it  never  acts  so  badly  here.  The  whole  chads  cana- 
plant  is  semitransparent,  with  leaves  about 
half  an  inch  long  springing  directly  from  the  stem,  and 
tapering  to  the  point.  These  leaves,  under  the  micro- 
scope, exhibit  a  remarkable  phenomenon. 

All  plants  are  formed  of  cells,  or  cavities  of  various 
sizes  and  shapes,  surrounded  on  all  sides  by  a  delicate 
membrane  called  the  cell  wall.  The  cells  are  seldom 
empty.  Their  contents  are  chiefly  the  soft,  colorless, 
jelly-like  substance  called  vegetable  protoplasm,  and  the 
small  green  grains  (the  chlorophyl)  which  give  the 
green  color  to  the  plant.  In  Andcharis  the  walls  of 
the  leaf -cells  are  transparent,  so  that  the  microscope 
shows  a  part  of  what  is  taking  place  within  the  cell ;  and 
it  is  a  wonderful  sight,  for  the  protoplasm  is  slowly 
moving  around  the  walls,  carrying  the  chlorophyl 
grains  with  it.  Up  one  side  of  that  microscopic  cell 
travels  the  strange  procession ;  across,  down,  and  up, 
slowly  and  steadily  the  stream  and  the  grains  move 
round  and  round.  Sometimes  a  little  thread  of  colorless 
protoplasm  leaves  the  main  current  and  starts  across  by 
a  shorter  road,  and  sometimes  the  current  pauses,  stops, 


60  MICROSCOPY  FOR  BEGINNERS. 

and  refuses  to  move  again.  The  streams  in  two  cells 
lying  side  by  side  may  flow  in  the  same  or  in  opposite 
directions,  with  only  the  thin  wall  between  them.  What 
causes  these  remarkable  movements  is  not  known.  Cold 
seems  to  retard,  and  warmth  to  hasten  the  flow,  and 
often,  when  the  chlorophyl  has  increased  so  that  the 
green  grains  crowd  the  cells,  the  circulation  ceases,  ap- 
parently because  the  chlorophyl  has  not  enough  space 
for  free  movement.  The  botanists  call  this  circulation 
of  the  protoplasm  cyclosis.  It  is  also  finely  seen  in  the 
long,  narrow,  ribbon-like  leaves  of  Vallisneria,  an  abun- 
dant and  common  plant  in  slowly  flowing  streams. 

To  show  the  cyclosis,  the  Anacharis  leaf  needs  only 
to  be  cut  close  to  the  stem,  placed  in  the  cell  in  water, 
covered  by  a  thin  glass,  and  examined  by  a  high-power 
objective.  The  one-inch  glass  will  not  show  it.  . 

The  plant  is  a  fruitful  source  of  supply  for  our  two 
common  species  of  Hydra  (Chapter  YL),  which  often  oc- 
cur there  so  plentifully  that  two  or  three  hang  from  al- 
most every  leaf. 

SPHAGNUM  MOSS  (Fig.  15). 

On  the  wet  shores  of  shady  bogs  this  pale -green 
moss  grows  in  great  patches,  thick,  soft,  and  elastic.  It 
is  a  beautiful  plant  anywhere,  but  it  is  especially  so 
when  it  appears  greenly  glimmering  beneath  the  shallow 
water,  while  the  shadows  of  elder  and  azalea,  and  the 
broad  leaves  of  the  tangled  smilax  vines,  make  the 
neighboring  thicket  dim  and  cool,  even  when  the  hot 
sun  smites  the  bordering  fields.  In  such  pleasant  sur- 


AQUATIC  PLANTS  USEFUL  TO  THE  MICROSCOPIST.      61 


roundings  Rhizopods  (Chapter  IY.)  and  Infusoria  (Chap- 
ter "V.)  are  found  in  abundance.  For  the  former  it  is 
an  unfailing  source  of  supply.  The  water  pressed  out 
of  a  little  pinch  of  the  moss  will  be  sure  to  contain 
many  individuals  and  species.  From  a  single  small 
bunch  Dr.  Leidy,  when  studying  the  Rhizopods,  ob- 
tained thirty-eight  species  and  many  individuals  of  those 
animals,  besides  numerous  active  diatoms  (Chapter  III.) 
and  desmids  (Chapter  III.). 

The  leaves  make  exquisite  microscopic  objects,  on  ac- 
count of  their  curious  and  beautiful  structure.     Each 
leaf  is  formed  of  two  kinds 
of  cells,  a  and  &  (Fig.  15). 
The   large    ones,  a,  will, 
when  magnified,  immedi- 
ately attract  the  attention. 
They  are  hollow,  and  usu- 
ally empty,  and  they  have 
a   spiral   thread    running 
around  the  walls.    At  cer- 
tain stages  of  growth  the 
cell -wall  also  has  one  or 
more    small   openings,  c, 
so  that  the  water  is  able 
to  pass  in  and  fill  the  cell. 
This  may  explain  why  the     Fig"  15-p-tio»  of  Leaf  of  sphagnum, 
plant  retains  moisture  for  so  long,  and  why  it  is  so 
easily  wetted. 

The  second  kind  of  cells,  5,  are  found  between  the 


62  MICROSCOPY  FOR  BEGINNERS. 

large  ones.  They  are  much  smaller,  narrower,  and  com- 
monly contain  chlorophyl  grains,  which,  while  usually 
not  abundant  enough  to  tint  the  whole  moss  a  bright 
green,  yet  give  it  that  beautiful  pale  hue  almost  charac- 
teristic of  it.  These  cells  will  probably  need  to  be 
searched  for  the  first  time  the  beginner  studies  a  sphag- 
num leaf,  as  they  are  not  apt  to  catch  the  eye. 

The  moss  seems  to  have  no  roots.  The  lowest  parts 
of  the  thick  mass  which  it  makes  are  usually  dark  and 
partially  decayed,  and  it  is  there  that  the  Rhizopods  are 
most  abundantly  found,  although  many  sun-loving  forms 
are  equally  numerous  in  the  brighter,  better  lighted  up- 
per parts.  On  no  account  should  the  student  pass  a 
sphagnum  swamp,  nor  even  a  little  patch  in  those  places 
where  it  grows  more  rarely,  without  taking  some  to  be 
examined  at  home.  Such  a  gathering  will  always  pay. 

R1CCIA  FLUITANS  (Fig.  16). 

Near  the  writer's  home  this  little  floating  plant  (pro- 
nounced ricksia)  is  so  abundant  that  it  often  covers 
small  pools  with  a  layer  two  inches  deep. 
Elsewhere,  on  larger  ponds,  it  is  not  un- 
common. It  often  comes  to  the  collect- 
ing-bottle tangled  in  the  leaves  of  Utricu- 
laria,  Myriophyllum,  or  Ceratophyllum, 
Fig.  16.— Kiccia  flfi-  or  it  floats  on  still  waters  in  little  patches 

iUms. 

like  islands.  Its  form  is  seen  in  Fig.  16. 
It  has  no  leaves,  indeed  it  is  all  leaf ;  the  botanist  calls 
it  a  radiately  expanding  frond,  with  narrow  divisions, 


AQUATIC  PLANTS   USEFUL   TO   THE   MICROSCOP1ST.      63 

whose  ends  are  notched.  The  plant  is  green,  and  may 
be  an  incli  or  more  wide  when  spread  out.  It  is  often 
larger  and  more  branched  than  shown  in  the  figure. 
It  has  no  roots,  but  floats  freely  wherever  the  currents 
or  the  winds  send  it.  Shady  places  seem  its  favorite 
haunts. 

As  a  microscopic  object  it  is  rather  large  and  thick, 
but  it  forms  a  good  place  to  examine  for  certain  Algae 
(Chapter  III.)  which  tangle  themselves  about  it  in  fine 
green  threads,  appear  to  favor  it,  and  may  often  be  seen 
with  the  naked  eye  if  the  single  frond  is  placed  in  water 
above  a  wliite  surface. 


64:  MICROSCOPY  FOR  BEGINNERS. 


CHAPTER  III. 

DESMIDS,  DIATOMS,  ASTD   FRESH-WATER   ALG.E. 

THE  desraids  and  diatoms  are  two  closely  related 
groups  of  minute  aquatic  plants  which  the  beginner 
will  at  first  probably  have  some  trouble  to  distinguish 
from  each  other ;  yet  after  a  very  little  experience  he 
will  be  able  to  recognize  them  at  a  glance.  Both  are 
plants  formed  of  only  a  single  cell,  but  their  beauty  and 
variety  of  form,  their  peculiar  movements  and  wonder- 
ful structure,  place  them  among  the  most  attractive  of 
microscopic  objects.  And  they  are  among  the  most  fre- 
quent. Scarcely  a  drop  of  water  from  a  pool  in  spring 
or  summer  can  be  examined  without  showing  a  desmid 
or  a  diatom. 

The  desmids  are  usually  found  in  the  freshest  and 
sweetest  water.  In  salt  or  brackish  marshes,  where  di- 
atoms flourish  as  well  as  in  a  mill  -  pond,  desmids  never 
occur.  They  also  seem  to  prefer  open  pools  on  which 
the  sun  is  brightest  and  the  shadows  fewest,  where  they 
probably  seek  warmth  rather  than  the  strong  light,  for 
they  seldom  form  patches  on  the  mud  as  the  diatoms 
do,  but  adhere  to  the  stems  of  other  plants  in  a  green 
film,  or  conceal  themselves  among  the  dissected  leaves 
of  the  aquatic  vegetation,  or  among  tangled  masses  of 


DESMIDS,  DIATOMS,  AND  FRESH-WATER  ALG.E.         65 

A  living  desmid  is  always  green ;  a  living  diatom  is 
always  brown.  This  difference  in  color  makes  it  easy  to 
distinguish  the  two  groups  of  plants,  but  there  are  other 
points  that  can  be  used  by  even  a  color-blind  student. 
The  cell- wall  of  the  desmid— that  is,  the  thin  sack  which 
surrounds  the  soft  green  contents — is  soft  and  flexible. 
If  the  cover-glass  is  pressed  down  firmly  with  a  needle 
the  desmid  can  be  flattened  or  squeezed  out  of  shape, 
and  the  cell-wall  can  often  be  broken,  so  that  the  green 
and  colorless  mixture  of  jelly-like  matter  filling  the  plant 
is  forced  out.  The  cell-wall  of  a  diatom  is  hard  and  brit- 
tle. The  cover-glass  may  be  pressed  upon  until  the  glass 
breaks,  yet  the  diatom  will  not  be  flattened  nor  its  shape 
changed.  It  may  roll  over  and  look  quite  different  in 
form  when  viewed  in  another  position,  but  it  will  prob- 
ably roll  back  and  appear  as  at  first.  It  can  be  broken, 
however ;  and  it  does  so  as  if  made  of  glass  or  some  other 
hard  and  brittle  material,  and  the  yellowish-brown  con- 
tents may  flow  out,  but  the  broken  place  will  not  be  a 
hole  with  irregular  edges,  as  it  was  in  the  crushed  des- 
mid ;  the  edges  will  be  sharp  and  angular,  and  the  dia- 
tom will  probably  break  into  several  fragments.  Yet 
with  the  most  skilful  manipulation  it  is  rather  difficult 
to  purposely  break  any  but  the  largest  of  the  diatoms, 
few  of  which  are  visible  to  the  unaided  sight  of  the 
acutest  eye.  The  little  hard-coated  plants  are  often  found 
in  fragments,  but  according  to  the  writer's  experience 
they  are  broken  accidentally,  either  by  being  piled  on 
top  of  each  other  and  so  crushed  by  the  cover -glass, 


66  MICROSCOPY  FOR  BEGINNERS. 

or  by  the  rough  contact  with  one  another  when  gath- 
ered. 

The  desmids  float  freely  in  the  water ;  many  diatoms 
do  the  same.  Several  species  of  desmids  are  attached 
to  each  other  side  by  side  to  form  long  bands ;  many 
diatoms  are  arranged  in  a  similar  way.  Some  desmids 
are  surrounded  by  a  colorless  jelly-like  coating ;  so  are 
some  diatoms.  The  desmids  never  grow  on  the  ends 
of  stems  secreted  by  themselves,  and  attached  to  other 
plants  or  submerged  objects ;  many  diatoms  are  found 
growing  on  the  extremities  of  long  colorless  and  branch- 
ing stalks  like  microscopic  trees,  these  stems  being  fast- 
ened to  other  objects  in  the  water.  Some  of  the  common- 
est diatoms  will  be  found  in  great  abundance  growing  in 
this  way  on  the  leaves  of  Myriophyllum.  Any  object 
that  may  apparently  be  either  a  desmid  or  a  diatom  is 
not  a  desmid  if  it  is  on  the  end  of  a  stem  of  its  own 
formation.  Most  desmids  have  the  ability  to  voluntari- 
ly change  their  position.  They  can  move  from  place 
to  place,  as  they  frequently  do  when  under  the  micro- 
scope, slowly  travelling  across  the  field  of  view  in  a 
very  interesting  way.  "When  mixed  with  mud  or  dirt, 
as  they  often  are  when  gathered  and  carried  home  in  a 
bottle,  they  will  gradually  work  themselves 'to  the  sur- 
face and  collect  in  a  green  film  or  line  on  the  side  of 
the  bottle  next  the  window,  whence  they  can  be  easily 
taken  by  the  dipping -tube.  Diatoms  have  a  similar 
power  of  movement ;  but  they  are  usually  much  more 
active,  and  their  motions  more  rapid  than  those  of  des- 


DESMIDS,  DIATOMS,  AND  FRESH-WATER  ALG^E.          67 

mids.  And  wliile  the  desmids  move  stately  and  slowly 
in  one  direction,  a  diatom  may  travel  quickly  half-way 
across  the  field  of  view,  and  without  a  moment's  hesita- 
tion, and  without  turning  round,  may  at  once  return  by 
its  former  path  or  dart  off  obliquely.  A  moving  diatom 
always  seems  to  have  important  business  on  hand,  and 
to  be  anxious  to  accomplish  it.  An  object,  therefore, 
that  may  be  either  a  desmid  or  a  diatom  is  not  a  desinid 
if  it  moves  rapidly  and  changes  its  course  suddenly  and 
quickly.  The  cause  of  this  motion  is  in  either  case  a 
mystery.  Many  theories  have  been  proposed  to  explain 
it,  but  none  are  satisfactory.  If  the  reader  can  discover 
how  the  desmids  and  diatoms  move  themselves  his  name 
will  be  remembered  among  naturalists  to  the  end  of 
time. 

The  surface  of  a  desmid  may  be  smooth,  finely  stri- 
ated lengthwise,  roughened  by  minute  dots  or  points,  or 
it  may  bear  several  wart-like  elevations  or  spines  of  dif- 
ferent shapes ;  its  edges  may  be  even  or  notched,  pro- 
longed into  teeth,  or  variously  cut  and  divided.  It  is 
these  ornaments,  in  connection  with  the  graceful  form 
and  the  pure  homogeneous  green  color,  that  make  the 
desmids  so  attractive  to  every  student  of  microscopic 
aquatic  life.  Fresh-water  diatoms  occasionally  have  tooth- 
like  processes,  but  they  are  never  spine-bearing ;  yet  the 
markings  of  their  surfaces  are  among  the  most  exquisite 
of  Nature's  handiwork,  and  the  most  varied.  Dots,  hem- 
ispherical bosses,  hexagons,  transverse  and  longitudinal 
lines  of  astonishing  fineness,  are  among  their  many 
4* 


68  MICROSCOPY  FOR  BEGINNERS. 

surface  sculpturings,  the  delicacy  and  the  closeness  of 
which  defy  description.  So  fine  and  close  together  are 
the  surface  lines  of  some  that  they  are  used  to  test  the 
good  qualities  of  the  best  and  highest  power  objectives: 
There  are  no  perfectly  smooth  diatoms,  although  many 
may  appear  so  to  a  low-power  lens ;  but  the  splendid 
glasses  of  the  best  American  makers  will  compel  any 
diatom  to  show  just  how  it  is  marked  and  roughened. 

In  each  end  of  many  desmids,  especially  in  the  cres- 
cent-shaped ones,  is  a  small  colorless,  apparently  circu- 
lar space  containing  numerous  very  minute  black  parti- 
cles in  incessant  motion.  These  little  granules,  which 
are  said  to  be  crystals,  are  sometimes  so  few  that  they 
can  be  counted  if  sufficiently  magnified,  while  in  other 
individuals  they  are  innumerable.  Their  motion  resem- 
bles the  swarming  of  microscopic  bees.  It  can  scarcely 
be  described,  but  once  seen  it  can  never  be  forgotten. 
The  spaces  containing  them  are  called  vacuoles,  and  are 
never  present  in  diatoms.  It  is  true  that  in  some  of 
the  latter,  when  dying  or  dead,  many  minute  black  par- 
ticles are  visible,  dancing  and  swarming  in  clusters  with- 
in the  cells,  but  this  is  common  to  many  microscopic 
creatures  after  death.  In  the  desmids  there  is  also  often 
seen  a  circulation  of  the  protoplasm  similar  to  the  cy- 
closis  in  the  leaf-cells  of  Anacharis,  a  movement  of  the 
cell  contents  never  observed,  so  far  as  I  am  aware,  in 
any  diatom.  Between  the  cell-wall  and  the  green  col- 
oring matter,  the  chlorophyl,  there  seems  to  be  a  nar- 
row space  filled  with  colorless  protoplasm,  and  it  is  here 


DESMIDS,  DIATOMS,  AND  FKESH-WATER  ALG.E.       69 

that  the  circulation  takes  place.  It  is  a  steady,  quite 
rapid  flow,  several  currents  streaming  lengthwise  up  and 
down  the  cell,  carrying  the  minute  starch  grains  and 
other  enclosed  particles  in  their  course.  It  has  been 
said  that  these  currents  sometimes  enter  the  vacuoles, 
and  that  the  latter  obtain  their  supply  of  swarming 
granules  from  the  particles  in  the  streams ;  it  has  also 
been  stated  that  occasionally  one  or  more  of  the  swarm- 
ing granules  leaves  the  vacuole,  enters  the  current,  and 
journeys  round  the  cell.  These  statements  are  rather 
doubtful.  But  with  a  high -power  objective  (the  one- 
fifth,  for  instance)  it  is  not  difficult  to  select  a  granule, 
and  follow  it  as  the  current  carries  it  down  one  side  to 
the  vacuole,  where,  according  to  the  writer's  observation, 
it  never  enters,  but  passes  into  an  ascending  current, 
and  continues  the  round.  The  vacuoles  themselves  are 
visible  with  a  good  low-power  objective,  but  to  see  the 
swarming  granules  and  the  general  cyclosis  a  one-fourth 
or  one-fifth  is  needed. 

In  addition  to  the  desmids  and  diatoms,  almost  every 
pond  and  stream  contains  other  minute  plants  of  interest 
to  the  microscopist,  called  the  fresh-water  Algae,  which 
he  probably  already  knows,  if  not  by  this  name,  at  least 
by  their  general  appearance,  for  they  form  those  green 
masses  floating  like  a  scum  on  the  surface,  or  soft  green 
clouds  attached  to  sticks  and  stones  and  dead  leaves. 
The  Algse  often  have  a  disgusting  appearance  as  they 
collect  in  thick  and  heavy  patches,  but  under  the  micro- 
scope they  reveal  beauty  undreamed  of.  All  those  slimy, 


70  MICROSCOPY  FOR  BEGINNERS. 

slippery  streamers  usually  so  abundant  in  still  water  dur- 
ing the  summer  are  Algse.  The  beginner  need  have  no 
trouble  to  recognize  them  as  Algse  after  a  little  experi- 
ence, but  since  he  at  first  may  be  somewhat  uncertain 
as  to  which  of  the  three  classes  of  plants  his  specimen 
belongs,  the  following  Key  has  been  constructed  to  aid 
him.  To  use  it,  compare  the  plant  with  it  in  the  fol- 
lowing way : 

Suppose  the  specimen  is  a  single  cell,  shaped  like  a 
crescent,  as  described  in  the  first  sentence  of  the  Key. 
The  reader  will  notice  (a)  at  the  end,  meaning  that  he 
shall  now  seek  a  description  somewhere  in  the  table  be- 
low with  a  at  the  head  of  the  line.  Finding  three  such 
lines,  he  reads  the  first,  "Color  green,"  which  is  the 
color  of  the  specimen  under  the  microscope ;  "  the  plant 
a  floating  hollow  sphere,"  which  does  not  describe  it, 
since  it  is  crescent-shaped.  He  then  reads  the  second 
"a"  line :  "  Color  green,  the  plant  not  a  hollow  sphere," 
which  is  of  course  right,  as  his  plant  is  not  a  sphere. 
The  (£>)  at  the  end  refers  to  another  line  below  headed 
by  5.  There  being  but  one  such,  the  plant  must  be  a 
desmid ;  but  to  learn  which  of  the  numerous  desmids  it 
is,  he  turns  to  Section  I.  of  this  chapter,  where  is  another 
Key  to  help  him  find  the  name  of  the  genus.  Again,  sup- 
pose he  obtains  a  floating  mass  which,  when  lifted  on  the 
hand  or  in  the  dipper,  he  sees  to  be  a  fine,  delicate  green 
net.  To  find  the  section  to  which  this  belongs,  read  each 
numbered  sentence  at  the  beginning  of  the  Key :  1  will 
not  do,  since  the  specimen  is  not  spherical,  crescentic, 


DESMIDS,  DIATOMS,  AND  FRESH-WATER  ALG.E.         71 

nor  circular ;  2  will  not  do,  because  the  plant  is  not  in 
long  threads ;  3  and  4  do  not  describe  it,  because  it  is 
neither  star -shaped  nor  formed  of  oval  cells  with  two 
bristles  on  each  end ;  but  5  calls  for  a  green  net  often 
visible  to  the  naked  eye,  which  describes  the  specimen, 
giving  the  name  of  its  genus,  Hydrodictyon,  and  refer- 
ring the  student  to  the  Algse,  Section  III.  of  this  chap- 
ter. After  using  this  preliminary  Key  for  a  few  times, 
he  will  be  able  to  .decide  at  a  glance  through  the  micro- 
scope to  which  section  his  specimen  belongs. 

Key  to  the  Desmids,  Diatoms,  and  fresh-water  Algce. 

1.  Plants  formed  of  a  single,  crescent-shaped,  spherical, 

barrel  -  shaped,  oblong  and  constricted,  or  circular 
and  flattened,  cell,  sometimes  arranged  side  by  side 
in  long  ribbons,  but  seldom  end  to  end ;  color  green 
or  brown  (a). 

2.  Plants  formed  of  many  cells  arranged  end  to  end  in 

long  threads ;  coloring  matter  usually  green,  often 
in  spiral  bands  or  other  patterns  on  the  cell-wall  (d). 

3.  Plants  formed  of  several  green  cells  grouped  in  the 

shape  of  a  flat  disk  with  six  to  many  short  blunt  star- 
like  points ;  floating  free.  Pedidstrum  (Algce,  III.). 

4.  Plants  formed  of  two  to  eight  narrowly -oval  green 

cells  placed  side  by  side,  each  terminal  cell  with 
two  curved  colorless  bristles;  floating  free.  See* 
nedesmus  (Algce,  III.). 

5.  Plants  forming  a  green  net  visible  to  the  naked  eye. 

Hydrodictyon  (Algce,  III.). 


72  MICROSCOPY  FOR  BEGINNERS. 

a.  Color  green,  the  plant  a  floating  hollow  sphere. 

V61VOX  (AlffCB,  III.). 

a.  Color  green,  the  plant  not  a  hollow  sphere  (5). 

a.  Color  golden-brown  (c). 

1).  Cell-wall  smooth,  rough,  warty,  or  spine-bearing, 
also  soft  and  flexible;  always  floating  freely, 
never  growing  on  stems  permanently  attached  to 
other  objects  ;  a  vacuole  with  swarming  granules 
often  present  in  each  end.  (Desmids,  /.) 

c.  Cell-wall  marked  transversely,  often  also  longitudi- 

nally, by  lines,  smooth  bands,  or  dots;  never 
spine-bearing ;  cell-wall  also  hard  and  brittle ; 
floating  freely,  or  growing  on  colorless  stems 
permanently  attached  to  other  objects.  (Dia- 
toms, II.} 

d.  Plants  forming  cloud-like  clusters,  long  streamers, 

or  scum-like  floating  masses  visible  to  the  naked 
eye ;  color  bright  green  or  olive,  sometimes  al- 
most black ;  the  cells  under  the  microscope  unit- 
ed end  to  end  to  form  long,  sometimes  branching 
filaments.  (Algce,  III.) 

1.  DfcSMIDS. 

As  the  desmids  are  singly  invisible  to  the  naked  eye, 
the  student  can  know  what  he  has  gathered  only  after 
reaching  home,  except  in  those  rare  instances  where  the 
little  plants  have  become  congregated  together  in  such 
quantities  that  a  good  pocket-lens  will  show  their  forms. 
I  have  more  than  once  found  Clostirium  in  this  profu- 


DESMIDS,  DIATOMS,  AND  FRESH-WATER  ALG^E.         73 

sion,  but  never  any  other.  The  early  spring,  as  early 
as  the  last  of  March  or  the  first  of  April,  in  the  writer's 
locality  (New  Jersey),  is  the  best  time  of  the  year  to 
gather  them,  or  indeed  any  of  the  Algae.  At  that  time 
all  these  plants  seem  more  vigorous,  their  vital  functions 
are  performed  more  actively,  and  the  observer  is  then 
almost  sure  to  see  in  some  of  them  the  conjugation,  or 
union,  of  two  separate  cells  and  the  formation  of  the 
spores.  This  spore  formation,  however,  is  much  more 
frequently  seen  in  the  thread-like  Algae  than  in  the  sin- 
gle-celled desmids. 

There  are  more  than  four  hundred  known  species  of 
desmids.  Perhaps  an  undue  proportion  has  been  in- 
cluded in  the  subsequent  list,  but  nature  offers  them 'so 
freely  and  abundantly,  and  they  are  so  attractive,  that 
they  must  be  their  own  excuse. 

The  following  Key  to  the  genera  is  to  be  used  as 
directed  for  the  "  Key  to  the  Desmids,  Diatoms,  and 
Fresh-water  Algae,"  except  that  when  the  name  of  the 
genus  has  been  found,  the  reader  should  then  refer  to 
the  paragraph  on  the  following  pages  headed  by  that 
name,  where  he  will  find  one  or  more  species  described 
and  figured.  Thus,  if  he  has  a  green  half-moon-shaped 
plant  under  the  microscope,  to  learn  its  name  turn  to 
this  Key,  the  second  line  of  which  describes  it,  since  it 
is  not  in  ribbons  or  bands ;  he  then  refers  to  the  lines 
headed  by  d,  the  first  one  describing  his  plant  as  a  "  cell 
more  or  less  crescent-shaped,"  giving  the  generic  name 
Closterium,  6  being  the  number  of  the  paragraph  fur- 


74  MICROSCOPY   FOR  BEGINNERS. 

ther  on  in  this  section  of  the  chapter,  where  several 
species  are  noticed. 

Key  to  Genera  of  Desmids. 

1.  In  ribbons  or  narrow  bands  (a). 

2.  Not  in  ribbons  nor  bands  (d}. 

a.  In  a  transparent,  jelly-like  sheath  (5). 

a.  Not  in  a  jelly-like  sheath  (c). 

I.  Each  cell  with  two  teeth  on  eacli  narrow  end. 

Didymoprium,  1. 
5.  Each  cell  deeply  divided  almost  into  two   parts. 

Sphcerozosma,  2. 

b.  Each  cell  without  teeth  and  not  divided.     Hyalo- 

theca,  3. 

c.  Cells  barrel-shaped,  the  band  not  twisted.     Bam- 

busina,  4. 

c.  Cells  not  barrel-shaped,  the  band  twisted.     Desmi- 

dium,  5. 

d.  Cell  more  or  less  crescent -shaped.     Closterium, 

6. 

d.  Cell   cylindrical,   spindle-shaped,   hour-glass,  or 
dumb-bell  shaped  (/). 

d.  Cell  flattened,  oblong,  circular,  or  often  divided 

into  arms  (e). 

e.  Mostly  circular  or  broadly  elliptical,  often  cut  and 

divided  by  slits  and  depressions ;  marginal  teeth 
usually  sharp.     Micrasterias,  Y. 
e.  Mostly  oblong  or  elliptical,  the  margin  wavy,  the 
depressions  rounded.     Euastrum,  8. 


DESMIDS,  DIATOMS,  AND  FRESH-WATER  ALG.E.         75 

f.  Cell  constricted  in  the  middle  ;  no  arms  nor  sharp 
spines  (g). 

f.  Cell  constricted  in  the  middle,  with  arms  or  sharp 

spines  (A). 

f.  Cell  not  constricted  in  the  middle ;  no  arms  nor 
sharp  spines  («"). 

g.  Ends  notched,  cell  cylindrical.     Tetmemorus,  9. 

g.  Ends   not  notched,   cell  cylindrical.     Docidium, 

10. 
g.  Ends  not  notched ;  cell  more  or  less  dumb-bell  or 

hour-glass  shaped  (I). 
h.  Arms  three  or  more,  radiating,  tipped  with  one  or 

more  points.     Staurastrum,  12. 
h.  Arms  none,  spines  four,  two  on  each  end.     Ar- 

throdesmuSj  14. 

h.  Arms  none;  spines  several,  on  the  edges;  a  round- 
ed, truncate,  or  denticulate  tubercle  in  the  centre 

of  each  semi-cell.     Xantladium,  13. 
*.  Chlorophyl  in  a  spiral  band,  cell  cylindrical.    Spi- 

rotcenid,  15. 

*.  Chlorophyl  not  in  a  spiral  band,  cell  cylindrical  (&). 
k.  Surface  roughened  by  tooth-like  elevations.     Tri- 

ploceras,  16. 
~k.  Surface  smooth,  ends  rounded,  neither  divided  nor 

notched.     JPenium,  17. 

L  End  view  three  to  six  or  more  angular  (m). 
I.  End  view  not  angular,  margins  smooth,  dentate, 

or  crenate,  without  spines;  ends  always  entire. 

Cosmdriwn,  11. 


76 


MICROSCOPY  FOR  BEGINNERS. 


m.  Angles  obtuse,  acute,  or  with  horn-like  prolonga- 
tions.   Staurdstrum,  12* 

1.   DlDYMOPRITJM. 

Each  cell  in  the  band  longer  than  broad ;  two  round- 
ed or  angular  teeth  on  each  narrow  end ;  case  or  sheath 
distinct,  colorless.  D.  Gremllii,  Fig.  17. 


Fig.  IT.— Didym6prium  Grevillii.  Fig.  IS.— Spbserozosma  pnlchra. 

2.  SPH^EROZOSMA. 

Each  cell  in  the  band  about  twice  as  long  as  broad, 
divided  on  both  ends  almost  to  the  middle ;  sheath  large, 
colorless.  Three  cells  are  shown  in  the  figure.  S.  pul- 
chra,  Fig.  18. 

3.  HYALOTHECA. 

The  ribbons  are  often  very  long,  and  the  narrow  ends 
of  each  cell  are  sometimes  slightly  constricted,  as  shown 
in  the  lower  part  of  the  figure,  but  the  depression  is 
never  deep  enough  to  form  teeth  ;  sheath  colorless.  H. 
dissiliens,  Fig.  19. 


Fig.  19.-IIyalotheca  dissiliens.  Fig.  20.—  Bambnsina  Brebissunii. 

4.  BAMBUSINA. 
The  cells  somewhat  resemble  barrels  or  casks  joined 


DESMIDS,  DIATOMS,  AND  FRESH-WATER  ALG.E.         77 

end  to  end,  with  two  narrow  hoop-like  elevations  around 
the  middle  of  each.     J2.  Brebissonii,  Fig.  20. 

5.  DESMIDITJM. 

The  twisted  appearance  of  the  band  is  due  to  the 
fact  that  each  cell  is  triangular,  as  may  sometimes  be 
seen  when  they  break  apart  and  float  over  on  end,  but 
the  three  angles  are  not  all  in  the 
same  line,  each  cell  being  turned  a 
little  to  one  side.     When  the  side 
of  the  band  is  looked  at,  it  is  these       Fig.2i.-Desmidium 

Swartzii. 

angles  that  are  seen  like  a  dark  ob- 
lique or  zigzag  line  traversing  the  ribbon.     Each  cell  is 
slightly  toothed  on  both  the  narrow  ends.     Common. 
D.  Swartzii,  Fig.  21. 

6.  CLOSTERIUM  (Figs.  22  to  31). 

All  the  species  of  this  genus  are  more  or  less  cres- 
cent-shaped, some  being  more  curved  than  others,  but 
none  having  exactly  straight  sides.  In  each  end  of  al- 
most every  one  will  be  seen  a  clear  circular  vacuole  con- 
taining many  small,  dark,  swarming  granules.  These 
have  already  been  referred  to,  as  has  the  movement  of 
the  protoplasm  between  the  cell-wall  and  the  layer  of 
green  coloring  matter.  Closterium  is  the  only  desmid 
in  which  this  cyclosis  can  be  seen  easily,  if  it  ever  oc- 
curs in  others.  There  are  thirty-five  species  of  the 
genus,  the  following  being  some  of  the  commonest. 
The  most  convex  margin  is  called  the  "  back ;"  the  con- 
cave border  the  "  ventrum." 


78  MICROSCOPY  FOR  BEGINNERS. 

Some  Species  of  Closterium. 

1.  Ends  not  lengthened  out  into  a  colorless  beak  (a). 

2.  Ends  lengthened  out  into  a  colorless  beak  (/"). 

a.  Back  slightly  convex,  the  whole  cell  slightly 
curved  (&). 

a.  Back  strongly  convex,  ventrum  nearly  straight  (<?). 

a.  Back  strongly  convex,  ventrum  strongly  concave, 
with  a  central  enlargement  (<rl). 

a.  Back  strongly  convex,  ventrum  without  a  central 
enlargement  (e). 

J.  Ventrum  nearly  straight ;  vacuoles  close  to  the 
rounded  ends ;  fifteen  or  twenty  chlorophyl  glob- 
ules in  a  central  longitudinal  row  in  each  semi- 
cell.  C.  linedtum,  Fig.  22. 


Fig.  22.— Closterium  line&tum. 

Ventrum  nearly  straight ;  body  tapering  towards 
the  rounded,  sometimes  curved,  ends ;  vacuoles 
small,  often  scarcely  visible.  C.juncidwn,  Fig.  23. 


Fig.  23.— Closterium  jnncidnm. 

b.  Yentrum  and  back  equally  curved ;  ends  tapering ; 

ten  to  fourteen  chlorophyl  globules  in  a  central, 
longitudinal  row  in  each  semi-cell;  vacuoles  very 
small.  C.  acerosum.  Fig.  2-i. 

c.  Ends  rounded ;  chlorophyl  often  arranged  in  nar- 


DESMIDS,  DIATOMS,  AND  FRESH-WATER  ALG^E.         79 


Fig.  2i.  —  Closterium  acer6sum. 

row,  longitudinal  bands  ;  chlorophyl  globules  nu- 
merous ;  vacuoles  near  the  ends  ;  cell  very  large. 
C.  Lunula,  Fig.  25. 


Fig.  25.—  Clost6rium  Luunla. 


d.  Ends  rounded  ;  chlorophyl  often  arranged  in  nar- 
row, longitudinal  bands  ;  chlorophyl  globules  of- 
ten numerous  ;  vacuoles  close  to  the  ends.  C. 
Elireiibergii,  Fig.  26. 


Fig.  2C.— Closterium  Ehrenbergii.  Fig.  2T — Closterium  acnminatmn. 

e.  Large,  crescent  -  shaped ;  centre  broad,  ends  acute, 
vacuoles  small.  C.  acumindtum,  Fig.  27. 

e.  Small,  crescent-shaped,  distance  between  the  ends 
about  ten  times  the  central  diameter;  centre  nar- 
row, vacuoles  indistinct.  C.  Didnce,  Fig.  28. 


Fig.  28 Closterium  Diauae.  Fig.  20 Closterium  Veuus. 

e.  Very  small,  crescent-shaped,  eight  to  twelve  times 
as  long  as  broad ;  centre  narrow,  ends  sharp, 
vacuoles  distinct.  C.  Venus,  Fig.  29. 


80  MICROSCOPY  FOR  BEGINNERS. 

/.  Each  beak  about  as  long  as  the  green  body,  some- 
times shorter ;  whole  cell  slightly  curved,  vacu- 
oles  usually  indistinct.  C.  rostrdtum,  Fig.  30. 


Fig.  30.— Closterium  rostiitum. 

f.  Each  beak  extremely  fine,  longer  than  the  spindle- 
shaped  green  body,  the  tips  alone  curved.  C.  se- 
taceum.  Fig.  31. 


Fig.  31.— Clost&'ium  setacenm. 
7.  MICRASTERIAS  (Figs.  32  to  39). 

Each  Micrasterias  is  divided  across  the  middle  into 
two  equal  and  similar  halves,  or  semi-cells,  by  a  deep 
slit,  the  sides  of  which  may  be  either  close  together 
or  somewhat  separated.  Both  semi-cells  are  also  very 
much  slit  and  notched,  but  both  in  the  same  way,  the 
description  of  one  half,  therefore,  applying  equally  well 
to  the  other.  There  are  forty-two  species  of  the  genus. 
The  beginner  must  expect  to  find  many  forms  not  in- 
cluded in  this  list,  which  contains  only  some  of  the  most 
common  in  the  writer's  vicinity. 

Some  Species  of  Jtficrasterias. 

1.  More  or  less  circular  in  outline  (a). 

2.  Not  circular ;  divided  into  radiating  arms  (5). 

3.  Not   circular ;  not  divided   into   arms ;  central   slit 

gaping  0). 


DESMIDS,  DIATOMS,  AND  FRESH-WATER  ALGJK.         81 


a.  Each  semi-cell  divided  by  four  deep  cuts  into  one 

end  and  four  side 

lobes,  each  side-lobe 

divided  by  a  short- 
er cut  into  two  sec- 
tions, each  section 

by  a   still   shorter 

cut     divided     into 

two  divisions,  each 

division  by   a  yet 

shorter  cut  divided 

into  two  parts,  and 

each  part  with  two 

teeth.     Desmid  very  large.    31.  radiosa,  Fig.  32. 
a.  Each  semi-cell  divided  by  four  cuts  into  one  end 

and  four  side  lobes,  each  side-lobe  divided  by  a 

shorter  cut  into  two  parts,  and  each  part  with 

two  teeth.     M.  rotdta,  Fig.  33. 


Fig.  32.— Micrasterias  radiosa. 


Fig.  33.— Micrasterias  rotata.          Fig.  34.— Micrasterias  truncata. 

a.  Each  semi-cell  divided  by  two  cuts  into  one  end 
and  two  side-lobes,  each  side-lobe  by  a  shorter  cut 
divided  into  two  parts,  and  each  part  with  two 


82 


MICKOSCOPY  FOR  BEGINNERS. 


teeth.  End-lobes  broad,  often  with  two  teeth  ori 
each  end.  M.  truncata,  Fig.  34. 
I.  Each  semi -cell  divided  by  deep  rounded  depres- 
sions into  four  tapering,  slightly  curved  arms, 
the  whole  desmid  having  eight  undivided  arms. 
M.  arcudta,  Fig.  35. 


Fig.  35.— Micras- 
t6riaa  arcu4ta. 


Fig.  SO.— Micrasterias 
dich6toma. 


Fig.  ST.— Micrasterias  Kit- 
chelii. 


b.  Each  semi -cell  divided  by  two  acute  depressions 
into  one  end  and  two  side  lobes,  each  side-lobe 
divided  by  an  acute  depression  into  two  short 
parts,  each  part  divided  by  an  acute  depression 
into  two  short  arms,  and  each  arm  with  two  teeth ; 
arms  of  the  end-lobes  each  with  two  teeth ;  the 
whole  desmid  with  twenty  short  arms.  M.  dicho- 
tomy Fig.  36. 


Fig.  SS.-Micraste'iias  6scitans.  Fig.  39.— Micrasterias  laticcps. 


DESMIDS,  DIATOMS,  AND  FRESH-WATER  ALGM.         83 

c.  Divided  into  one  end  and  two  side  lobes  (d). 

d.  Side -lobes  divided  by  a  shallow  notch  into  two 

parts  extending  beyond  the  end-lobes,  each  part 
with  two  teeth  on  both  ends.  M.  Kitchelii,  Fig. 
37. 

d.  Side-lobes  not  divided  into  two  parts,  but  extend- 
ing beyond  the  end-lobes.  M.  oscitans,  Fig.  38. 

d.  Side-lobes  not  divided  into  two  parts,  not  extend- 
ing beyond  the  end-lobes.  M.  Idticeps,  Fig.  39. 

8.  EUASTRUM  (Figs.  40,  41,  42). 

Euastrum  is  divided  into  two  halves  by  a  central  slit 
across  the  middle,  but  the  cell  is  never  circular  as  in 
Micrasterias,  and  the  margins  are  wavy,  never  sharply 
toothed.  The  ends  are  usually  notched.  There  are 
about  forty  species. 

1.  Each  half  oblong ;  an  end-lobe  present  in  both  halves, 
and  formed  by  a  short  rounded  cut  on  each  side. 
E.  cmssum,  Fig.  4.0. 


Fig.  40.— Ea&strura  cris-  Fig.  41 Enastrum  Fig. 42. —Euastrum 

sum.  didelta.  ansatnm. 

2.  Each  half  somewhat  triangular,  without  distinct  end- 
lobes  (a). 


84  MICROSCOPY  FOR  BEGINNERS. 

a.  Sides  wavy,  gradually  expanding  towards  the  cen- 
tral cut.    E.  didelta,  Fig.  41. 

a.  Sides  hardly  wavy,  suddenly  expanding  towards 
the  central  cut.     Small.     E.  ansdtum,  Fig.  42. 

9.  TETMEMORCS  (Figs.  43,  44). 

1.  Widest  in  the  middle,  the  ends  tapering.     T.  granu- 

Idtus,  Fig.  43. 

Fig.  43.— Tetmemorus  granuldtus.          Fig.  44.— Tetmfimorus  Brebiss6nii. 

2.  Not  widest  in  the  middle,  the  ends  not  tapering.    T. 

£reliss6nii,  Fig.  44. 

10.  DOCIDIUM  (Figs.  45,  46). 

1.  A  rounded  enlargement  on  each  side  of  the  central 
constriction.     D.  Bdculum,  Fig.  45. 


Fig.  45.— Docidinm  Bacnlum.  Fig.  46.— Docidium  crennlatum. 

2.  Two  or  more  small  enlargements  on  each  side  of  the 
central  constriction,  giving  the  edges  a  wavy  ap- 
pearance. D.  crenulatum.  Fig.  46. 

11.  COSMAKIUM  (Figs.  47,  48,  49,  50). 

The  ends  of  Cosmarium  are  never  notched  nor  in- 
cised.    They  may  be,  and  often  are,  rough  or  warty, 
hut  the  ends  are  always  entire.     There  are  about  one 
hundred  species.     The  following  are  common : 
1.  Surface  smooth  ;  cell  less  than  twice  as  long  as  broad, 


DESMIDS,  DIATOMS,  AND  FRESH-WATER  ALG^E.         85 


the  two  semi  -cells  evenly  rounded.      C. 
Fig.  47. 

2.  Surface  smooth;  cell  about  twice  as  long  as  broad, 
the  margins  of  each  semi-cell  slightly  sloping  tow- 
ards the  flattened  ends.  C.  pyramidatum,  Fig.  48. 


Fig.  47.—  Cosma-         Fig.  4S.— Cosma-       Fig.  49.— Cosma-        Fig.  50.—  Cosroa- 
riutn  Ralfcii.  rium    pyrami-          riiim  margari-          rinm  Brebiss6- 

datum.  tifernm.  nii. 


3.  Surface  roughened   by  rounded,  pearly   elevations. 

C.  margaritiferum,  Fig.  49. 

4.  Surface  roughened  by  minute  sharp  points.     C.  Bre- 

bissonii,  Fig.  50. 

12.  STAURASTRUM  (Figs.  51,  52,  53,  54). 

In  front  view,  or  in  the  position  in  which  the  desmids 
usually  lie  naturally,  Staurastrum  resembles  Cosmarium, 
but  in  end  view  it  is  always  angular.  It  is  sometimes 
rather  troublesome  to  get  Staurastrum,  or  indeed  any 
other  desmid,  tilted  up  on  end  so  that  it  can  be  exam- 
ined in  that  situation,  but  in  a  moderately  deep  cell, 
with  considerable  water  and  a  low-power  objective,  it 
can  usually  be.turned  over  by  gently  tapping  and  press- 
ing the  cover-glass  with  a  needle. 

Staurastrum  is  a  large  genus,  containing  about  one 
hundred  and  twenty  species. 
1.  Cell  dumb-bell  shaped  ;  without  arms ;  surface  rough- 


86  MICROSCOPY  FOR  BEGINNERS. 

ened  by  small  elevations.     St.  punctuldtum,  Fig. 
51. 

2.  Cell  not  dumb-bell  shaped  ;  with  arms  (a). 
a.  Cell  triangular  in  end  view,  the  angles  toothed ; 
arms  in  a  cluster  of  about  three  on  the  end  of 
the  cell,  their  ends  toothed.    St.furcigerum,  Fig. 
52. 


Fig.  51.—  Stanr&-      Fig.  52.—  Stanra-      Fig.  53.— Stnnra-     Fig.  54.-Stanrastruni 
strum  punctnla-         strum  furcigc-         strum  gracile.  macnkerum. 

turn.  rum. 

a.  Cell  triangular  in  end  view,  the  angles  prolonged 
as  narrow  arms,  the  ends  of  which  are  three- 
toothed  ;  surface  roughened.  St.  ffrdcile,  Fig.  53. 

a.  Cell  with  six  or  seven  radiating  arms,  their  ends 
three-toothed.  St.  macrocerum,  Fig.  54. 

13.  XANTHIDIUM  (Figs.  55,  56). 

The  cells  bear  near  both  ends  a  prominence  or  tuber- 
cle that  may  be  rounded  and  smooth,  truncate,  or  appar- 
ently encircled  by  small  beads. 

1.  Cell  about  twice  as  long  as  broad ;  spines  short,  their 

ends  irregularly  toothed ;  tubercles  circular,  beaded. 
This  is  the  only  species  with  toothed  spines.  X. 
armdtum,  Fig.  55. 

2.  Cell  not  twice  as  long  as  wide,  each  half  somewhat 

kidney-shaped;  spines  in  four  or  six  pairs  on  each 


DESHIDS,  DIATOMS,  AND  FRESH-WATER  ALGJS.         87 

semi-cell,  not  divided  nor  toothed,  but  often  curved ; 
tubercle  a  curved  row  of  bead-like  elevations.  X. 
antilopceum,  Fig.  56. 


Fig.  55.— Xanthidium  armatum.         Fig.  56.— Xanthidium  autilopseum, 

14.  ARTHRODESMUS  (Figs.  57,  58). 

1.  Spines  on  the  same  side  curving  or  spreading  from 

each  other ;  surface  smooth.     A.  incus,  Fig.  57". 

2.  Spines  on  the  same  side  curving  towards  each  other ; 

surface  smooth.     A.  convergens,  Fig.  58. 


Fig.  57.— Arthrodesmus         Fig.  58.— Arthrodesmus         Fig.  59.—  Spirotsenia  con- 
incus,  couvergens.  deusata. 

15.  SPIROTSENIA. 

Ends  rounded ;  spiral  band  closely  wound.  £  con- 
densdta,  Fig.  59. 

16.  TRIPLOCERAS. 

Surface  roughened  by  small  projections  arranged  in 
rows  around  the  cell,  their  tips  notched  or  finely  toothed; 
cell  twelve  to  twenty  times  as  long  as  broad.  T.  verti- 
cilldtum,  Fig.  60. 


Fig.  CO.—  Triploceras  verticillatuin. 


88  MICROSCOPY  FOR  BEGINNERS. 

17.  PENITTM. 

Cylindrical ;  ends  rounded,  surface  smooth.  P.  Bre~ 
bissonii,  Fig.  61. 

If  it  is  desired  to  preserve  any  of  the  desmids  or 
Algae,  the  following  solution  will  be  found  to  be  an  ex- 
cellent medium.     In  it  the  plants 
retain  their  green  color,  and  the 
cell  contents  have  less  tendency 

Ffeei.-Pfiulnmlhebtarfoll.       ^   ^^  ^^   ^  ^^  than 

with  any  other  of  the  many  media  often  recommended. 
Any  druggist  can  make  the  solution.  It  is  composed 
as  follows :  Camphorated  water  and  distilled  water, 
of  each  50  grammes ;  glacial  acetic  acid,  0.5  gramme ; 
crystallized  chloride  of  copper  and  crystallized  nitrate 
of  copper,  of  each  2  grammes ;  dissolve  and  filter. 

The  plants  should  be  placed  in  a  cell  made  of  shellac, 
a  few  drops  of  this  preservative  copper-solution  added, 
and  the  cover  fastened  down  with  shellac.  If  any  other 
cement,  except  perhaps  Brown's  rubber  cement,  is  used 
with  this  solution  it  will  inevitably  run  under  and  ruin 
the  preparation. 

If  the  beginner  should  find  the  desmids  so  attractive 
that  he  desires  to  study  them  rather  than  to  learn  the 
names  and  appearance  of  a  few  of  the  commonest,  he 
should  refer  to  the  Kev.  Francis  Wolle's  excellent  book 
entitled  "  The  Desmids  of  the  United  States." 


DESMIDS,  DIATOMS,  AND  FRESH-WATER  AIXLE.         89 


II.  DIATOMS. 

For  a  long  time  there  was  much  discussion  as  to  the 
animal  or  vegetable  nature  of  the  diatoms,  but  that  they 
are  plants  is  now  the  general  belief.  Their  peculiar 
motion  was  one  great  reason  for  classing  them  among 
the  animals,  although  some  undoubted  plants  have  even 
a  more  rapid  movement. 

No  class  of  microscopic  objects,  except,  perhaps,  the 
Infusoria,  is  so  abundant.  No  ditch  or  pond  is  with- 
out them.  'No  pool  is  too  small  to  harbor  them ;  even 
a  depression  made  by  a  cow's  hoof  in  a  wet  meadow 
soon  becomes  a  home  for  them.  They  will  probably 
form  some  of  the  first  things  to  attract  the  attention 
of  the  beginner  in  the  use  of  the  microscope. 

Their  shape  is  as  varied  as  their  number  is  great,  and 
their  hard  and  glass-like  surface  is  most  beautifully 
lined  and  dotted,  and  sculptured  in  delicate  tracery. 
Most  plants  are  comparatively  soft,  but  the  diatoms  are 
noteworthy  for  the  hard  case  enclosing  the  semi-fluid, 
yellowish-brown  contents,  a  case  that  is  indestructible. 
It  may  be  heated  to  redness,  it  may  be  boiled  in  strong 
acids  and  alkalies,  and  at  the  end  be  as  it  was  before,  as 
gracefully  formed  and  as  beautifully  marked.  Indeed, 
to  properly  study  the  diatoms  they  should  be  treated 
by  some  method  to  destroy  the  coloring  matter  often 
obscuring  the  surface  markings  for  which  they  are 
chiefly  valued.  For  the  beginner,  however,  who  desires 
only  to  recognize  a  diatom  when  he  meets  with  one 


90  MICROSCOPY  FOR  BEGINNERS. 

in  the  field  of  his  microscope,  and  to  learn  its  name,  if 
possible,  such  preparation  is  unnecessary. 

Diatoms  are  also  peculiar  in  their  structure.  In  this 
they  have  often  been  compared  to  a  pill-box.  The  dia- 
tom is  formed  of  two  parts  called  valves,  one  of  which 
may  be  likened  to  the  pill-box  proper,  and  the  other  to 
the  lid,  since  it  slips  over  the  edge  of  the  lower  valve. 
The  entire  box-like  diatom  is  called  the  frustule  ;  the 
surfaces  of  the  tipper  and  lower  valves  are  usually 
marked  and  shaped  alike,  and  are  called  the  sides.  But 
when  the  frustule  happens  to  be  turned  so  that  the  nar- 
rowest part,  or  that  part  corresponding  to  the  thickness 
of  the  pill-box,  and  called  the  front,  is  towards  the  ob- 
server, then  the  shape  is  so  different  from  that  of  the 
valves  as  to  puzzle  the  beginner.  If  in  doubt  about 
the  position,  gently  tap  the  cover-glass  with  a  needle, 
when  the  frustule  will  generally  roll  over  on  its  broad 
side.  This  seems  somewhat  bewildering  at  first,  but 
there  is  no  difficulty  if  it  is  borne  in  mind  that  the 
thickness  of  the  pill-box  corresponds  to  the  front  of 
the  frustule,  and  the  broad  surfaces  of  the  lid  and  bot- 
tom to  the  sides  of  the  valves, 

In  addition  to  the  ordinary  markings  on  the  valves — 
that  is,  the  transverse  lines  which  are  sometimes  so 
coarse  that  they  are  called  ribs — each  valve  frequently 
bears  a  line  or  narrow  smooth  band  down  the  middle, 
while  at  each  end  and  at  the  centre  there  is  often  a  small 
rounded  spot  resembling  a  circular  space,  but  being  in 
reality  an  elevation,  called  a  nodule. 


DESMIDS,  DIATOMS,  AND  FRESH-WATER  ALG^E.         91 

In  remote  ages  diatoms  existed  in  even  greater  num- 
bers than  at  present.  Immense  beds  of  fossil  frustules 
are  found  in  many  parts  of  the  world,  especially  in  our 
own  country.  In  Maryland  and  in  New  Jersey  diato- 
maceous  earth  is  obtained  containing  exquisite  forms. 
In  Virginia  a  certain  deposit  is  especially  renowned, 
since  it  is  eighteen  feet  thick  and  underlies  the  city  of 
Richmond.  This  has  afforded  the  student  some  of  the 
rarest  and  most  valued  frustules,  or  valves,  for  the  frus- 
tule,  before  it  can  be  properly  studied,  must  be  sepa- 
rated into  its  two  valves.  To  have  produced  such  a 
mass  they  must  have  existed  in  incalculable  numbers  in 
a  great  body  of  water  where,  dying,  and  sinking  to  the 
bottom  year  after  year,  their  skeletons  accumulated  as 
others  continued  to  fall.  To  appreciate  the  probable 
length  of  time,  as  well  as  the  number  of  diatoms,  need- 
ed to  make  such  a  deposit,  it  is  only  necessary  to  know 
that  a  single  frustule  is  seldom  thicker  than  the  one 
ten-thousandth  of  an  inch. 

At  the  present  day  living  diatoms  are  often  found  in 
large  numbers  forming  a  yellowish-brown  film  on  the 
mud  in  shallow  water.  In  such  cases  it  is  no  trouble  to 
skim  them  up  and  so  gather  them.  Usually,  however, 
the  beginner  will  first  see  them  floating  freely  about  his 
slide,  or  attached  to  various  plants.  But  few  are  visi- 
ble to  the  naked  eye  except  when  collected  in  great 
masses,  and  only  then  as  brownish  patches ;  the  indi- 
vidual valves  are  seldom  seen  without  the  microscope, 
and  then  only  to  the  most  acute  and  best  educated  eye. 
5* 


92  MICROSCOPY  FOR  BEGINNERS. 

They  are  difficult  to  study  and  to  name.  To  prop- 
erly examine  them  demands  the  highest  power  object- 
ives of  the  best  construction,  and  a  skill  in  the  use  of 
the  microscope  and  accessary  optical  apparatus  not  at 
the  beginner's  command.  Much  has  been  written  about 
them,  but  the  literature  of  the  subject  is  so  widely  scat- 
tered through  the  scientific  magazines  that  only  those 
who  make  a  special  study  of  the  diatoms  can  hope  to 
have  it  in  their  libraries.  But  the  beginner  need  not 
despair.  With  ease  he  can  learn  to  recognize  a  diatom 
whenever  seen,  and  to  know  the  names  of  the  com- 
monest forms,  and  this  is  all  he  will  care  to  learn  at 
first.  Yet  he  will  find  it  a  satisfaction  to  be  able  to 
say  to  a  friend,  "  That  is  a  diatom,"  and  to  explain  its 
box-like  structure. 

The  following  Key  has  been  made  to  assist  the  be- 
ginner in  ascertaining  the  names  of  a  few  of  the  com- 
monest fresh-water  forms.  It  is  impossible  to  include 
even  a  tithe  of  the  plants,  and  the  beginner  will  surely 
find  many  not  mentioned  in  the  succeeding  list,  but 
from  the  brownish  color,  the  movements  common  to  so 
many,  and  the  hard,  dotted,  lined,  and  sculptured  valves, 
he  can  readily  know  them  as  members  of  the  Diatoma- 
ceae  after  he  has  seen  and  recognized  one.  More  than 
this  he  can  scarcely  hope  to  do. 

The  brown  coloring  matter  will  often  be  seen  con- 
tracted to  a  narrow  strip  or  to  a  spot  at  each  end,  and 
very  frequently  the  frustule  will  be  entirely  colorless. 
Diatoms  are  the  favorite  food  of  many  microscopic  ani- 


DESMIDS,  DIATOMS,  AND  FRESH-WATER  ALG^E.         93 

mals,  winch  absorb  the  cell  contents,  often  leaving  the 
hard  and  indigestible  valves  colorless,  but  otherwise  un- 
changed. 

Key  to  Genera  of  Diatoms. 

1.  Growing  in  bands  or  ribbons  (a). 

2.  Growing  on  colorless  stems  or  in  a  jelly-tube  (c). 

3.  Growing  with  their  concave  sides  attached  to  other 

plants  (e). 

4.  Free-swimming  (f\ 

a.  Band  curved  or  coiled.     Meridion,  1. 

a.  Band  zigzag ;  frustules  attached  together  by  the 
corners.  Didtoma,  2. 

a.  Band  uneven,  frustules  long,  narrow,  rapidly  slid- 
ing on  each  other.  Jfacilldria,  3. 

a.  Band  straight,  or  nearly  so,  edges  even,  frustules 

motionless  (i). 

b.  Each  frustule  six  times  as  long  as  broad.     Frage- 

Idria,  4. 

5.  Each  frustule  twice  as  long  as  broad.  Himanti- 
dium,  5. 

c.  In  a  narrow  jelly-tube ;  valves  boat-shaped.    En- 

cyonema,  6. 

c.  On  the  ends  of  colorless  stems  (d). 

d.  Valves  boat-shaped.     Cocconema,  7. 

d.  Valves  wedge-shaped.     Gomphonema,  8. 

e.  Valve  six  to  seven  times  as  long  as  broad.     Epi- 

themia,  9. 

e.  Valve  oval,  nearly  as  long  as  broad.  Cocconeis, 
10. 


94:  MICROSCOPY  FOR  BEGINNERS. 

f.  Valve  not  curved  nor  S-shaped  (g). 

f.  Valve  in  side  view  arched,  the  convex  edges  scal- 
loped. Eunotia,  11. 

f.  Valve  long  S-shaped.     Pleurosigma,  12. 

f.  Valve  boat -shaped,  the  ribs  conspicuous.  Suri- 
rella,  13. 

f.  Valve  boat-shaped,  ribs  none.     Namcula,  14. 

g.  Valve  strongly  ribbed  ;  a  nodule  at  each  end  and 

in  the  centre.     Pinnularia,  15. 
g.  Valve  not  ribbed  ;  with  a  central  longitudinal,  and 
,   a  transverse  smooth  band.     Stauroneis,  16. 

1.  MEKIDIOK  CIECULARE  (Fig.  62). 

Valves  wedge  -  shaped,  transverse  lines  indistinct, 
bands  spiral,  often  broken  into  small  curved  sections 
(Fig.  62). 


Fig.  62.— Meridion  circulare.  Fig.  63.-Diatoma  vnlgare. 

2.    DlATOMA  VTJLGARE  (Fig.  63). 

Frustules  oblong,  the  four  angles  right-angles,  band 
often  attached  to  aquatic  plants,  easily  separable  into 
its  component  frustules  (Fig.  63). 

3.  BACILLAKIA  (Fig.  64). 
Frustules  long  and  narrow,  united  laterally,;  freely 


DESMIDS,  DIATOMS,  AXD   FRESH-WATER  ALG^E.         95 

and  rapidly  sliding  backward  and  forward  over  each 
other ;  free-swimming  (Fig.  64). 

This  is  probably  one  of  the  most  interesting  of  the 
common  fresh-water  diatoms,  on  account  of  its  strange 
movements.   When  quiet,  as  it  prob- 
ably will  be  immediately  after  being        .   -r"~ ''-i    ;  * 
placed  on  the  slide,  the  band  will 

Fig.  64.-Bacillaria. 

somewhat  resemble  a  row  of  fence 
pickets  lying  closely  side  by  side.  Suddenly  each 
picket  shoots  forward  until  they  are  all  nearly  end  to 
end,  the  band  becoming  a  long  irregular  line,  and  quite 
as  suddenly  closing  together  again.  This  alternate  back- 
ward and  forward  gliding  is  continued  until  the  diatoms 
become  apparently  exhausted,  or  the  oxygen  in  the  wa- 
ter is  consumed.  What  prevents  one  frustule  from 
slipping  off  the  end  of  the  other  is  not  known ;  indeed 
the  cause  of  the  entire  performance  can  only  be  guessed 
at.  All  the  species  of  the  genus  Bacillaria  are  said  to 
live  in  salt  water.  The  form,  which  I  have  ventured  to 
identify  as  a  sweet-water  variety  of  B.  paradoxa  is  not 
uncommon  in  fresh-water  ponds. 

4.  FRAGELAIUA  CAPUCINA  (Figs.  65  and  65o). 
Frustules   very   narrow,  never   wedge- shaped,  band 
long.      Fig.  65  shows  the  band  of 
united  frustules ;  Fig.  65&  the  ap- 
pearance   of   a  single   valve  more 
highly  magnified.    The  ends  of  the 

Figs.  05  and  G5a.— Fragela- 

valves  are  somewhat  wTedge-shaped.  rtacnpndna. 


96  MICROSCOPY  FOR  BEGINNERS. 

5.    HlMANTIDIUM  PECTINALE  (Fig.  66). 

Frustules  much  wider  than  the  preceding,  transverse 
lines  distinct  on  both  sides  of  a  narrow  central  smooth 
space  (Fig.  66). 


Fig.  60.— Himantidium  pectinate.  Fig.  67.—  Encyonema  parad6xa. 

6.  ENCYONEMA  PARADOXA  (Fig.  67). 

The  jelly -tubes  are  usually  very  slightly,  if  at  all, 
branched,  the  frustules  commonly  arranged  in  longi- 
tudinal lines  within  the  tubes,  which  are  attached  to 
other  plants  (Fig.  67). 

7.  COCCONEMA  LANCEOLATA  (Figs.  68  and  68a). 
Stems    often   much   branched,  attached   to    aquatic 
plants  and  other  submerged  objects,  frustules  on  the 
ends  of  the  branches,  in   side   view  (valves)  slightly 
curved  with  a  median  longitudinal  line,  a 
nodule  at  each  end  and  in  the  centre  (Fig. 
68).     The  frustules  are  often  found  sepa- 
rated from  the  stems  and  floating  freely, 
when  they  are  usually  seen  in  side  view. 
Fig.  68#  shows  a  single  valve  highly  mag- 
nified. 

8.    GOMPHONEMA  ACUMINATA  (Fig.  69). 

Stems   often  much  branched,  but  fre- 
queiitly  found  uubranched ;    attached   to 

— Cocconema      *  J 

lanceoiata.       other  plants ;  frustules  slightly  swollen  in 


DESMIDS,  DIATOMS,  AND  FRESH-WATER  ALG.E.         97 

the  centre,  the  narrowest  end  of  the  wedge 
attached  to  the  stem  (Fig.  69). 

9.  EPITHEMIA  TURGIDA  (Fig.  70).m 
Valves  curved  or  bent,  transverse  lines 
coarse  and  conspicuous  (Fig.  70). 

10.  COCCONEIS  PEDICULUS  (Fig.  71). 
Valves  oval,  with  a  line  down  the  cen-  F'ls-  eo— 

iiema  acuininata. 

tre  and  a  small  nodule  in  the  middle ;  at- 
tached by  one  valve  to  aquatic  plants,  especially  to  the 
leaves  of  Andcharis  (Fig.  71). 


Fig.  70.—  Epithemia  tur-  Fig.  71.—  Cocconfts  Fig.  72.— Ean6tia 

gida.  pediculus.  '      tetraodou. 

11.    EUNOTIA  TETRAODON  (Fig.  72). 

Valves  curved,  a  small  nodule  at  each  end  of  the 
concave  margin ;  the  convex  border  apparently  scal- 
loped, but  in  reality  bearing  four  or  more  rounded 
ridges  (Fig.  72). 

12.    PLEUROSfGMA  (Fig.  73). 

Valves  long  S-shaped,  widest  in  the  middle  and  ta- 
pering to  both  ends,  one  of  which  curves  towards  the 


98  MICROSCOPY  FOK  BEGINNERS. 

right-hand  side,  the  other  towards  the  left-hand  (Fig. 
73).  A  narrow  S-shaped  line  extends  down  the  centre 
of  the  valve,  with  a  nodule  in  the  middle. 
There  are  a  large  number  of  species  of  this 
genus,  all  of  which  may  be  known  by  this 
peculiar  and  beautiful  curvature  of  the  sides, 
the  word  Pleurosigma  meaning  S- shaped 
sides.  The  valves  are  very  finely  striated, 
rig.  73.-pieu-  the  lines  being  remarkably  close  together, 
and  demanding  a  comparatively  high-power 
objective  of  excellent  construction  to  see  them.  The 
valves  are  therefore  often  used  to  test  the  good  quali- 
ties of  certain  objectives.  To  the  beginner,  however, 
all  the  Pleurosigmas  will  probably  appear  to  be  smooth. 
The  species  most  frequently  used  as  a  test  is  P.  angu- 
Idtum,  a  salt-water  form. 

13.    &UBIRELLA  SPLENDID  A  (Fig.  74). 

The  ribs  are  large  and  conspicuous,  the  spaces  be- 
tween them  seeming  to  be  lower  than  the 
edges  of  the  valves,  thus  giving  the  latter 
the  appearance  of  having  a  narrow  wing 
around  the  margin  (Fig.  74).  The  mem- 
bers of  this  genus  are  also  used  as  test- 
objects,  the  one  most  commonly  employed  ris.  74.1sarirei- 
being  a  marine  species.  la  8P16ndida- 

14.  NAVICULA  CUSPIDATA  (Fig.  75). 
Valves  widest  in  the  centre,  tapering  with  straight 


DESHIDS,  DIATOMS,  AND  FRESH-WATER  ALGyE.          99 

margins  to  eacli  end ;  a  straight  line  down 
the  middle  with  a  central  nodule  (Fig.  75). 

15.  PINNULARIA  (Figs.  76  and  77). 
1.  Sides  of  the  valves  parallel,  the  ends   Fig.  TJNavicu]a 
and  centre  somewhat  swollen ;  trans-        cuspidata. 
verse  ribs  large  and  conspicuous ;  a  line  down  the 
middle,  with  a  nodule  at  each  end  and  at  the  cen- 
tre ;  frustule  large.     Common.    P.  major,  Fig.  76. 


Fig.  76.—  Piuunlana  mnjor.  Fig.  77.—  Piumilariu  viridis. 

2.  Sides  of  the  valves  slightly  convex,  the  ends  and  the 
centre  not  swollen  ;  ribs  large  and  conspicuous  ;  a 
line  down  the  middle,  with  a  nodule  at  each  end 
and  one  in  the  centre  ;  frustule  smaller  than  the 
preceding.  It  is  named  green  (viri- 
dis),  probably  because  it  is  always 
brown.  P.  viridis,  Fig.  77. 


16.  STAURONEIS  PH<ENOCENTERON  (Fig.  78). 

Yalves  widest  in  the  middle,  tapering      terou- 
with  curved  sides  to  both  ends  ;  central  and  transverse 
bands  smooth  and  conspicuous.     Common  (Fig.  78). 

III.  FRESH-WATER  ALGJS. 

The  Algas  often  collect  together  and  form  green 
clouds  in  the  water  or  a  scum-like  growth  on  the  sur- 


100  MICROSCOPY  FOR  BEGINNERS. 

face.  Frequently,  however,  the  student  will  find  iso- 
lated filaments  under  his  microscope,  and  not  know  how 
they  were  placed  there,  or  he  will  find  single  threads 
adherent  to  other  objects  which  he  may  be  examining. 
The  color  of  the  visible  masses  is  usually  bright  green  ; 
it  may  be  brownish  if  the  plants  are  in  fruit,  or  the  nat- 
ural tint  of  the  individual  alga  may  be  brownish  or 
purplish.  Many  species  are  coated  with  a  mucous  or 
slimy  material  that  makes  them  very  slippery  and  diffi- 
cult to  handle,  or  to  remove  from  the  water  unless  a 
dipper  or  spoon  be  used. 

They  are  seldom  found  in  any  abundance  in  deep 
water.  They  seem  to  prefer  shallow  ponds  and  slowly 
flowing  streams,  where  they  may  have  plenty  of  warmth 
and  light.  Few  of  the  species  are  free  -  swimming. 
Most  kinds  are  adherent  to  leaves,  stones,  or  sticks  in 
the  water ;  some  form  feathery  clusters  of  branching  fil- 
aments, others  surround  themselves  by  little  balls  of 
translucent  jelly  often  attached  to  leaves  of  grass  or  to 
other  submerged  objects. 

The  following  have  been  partially  described  in  the 
Key  on  page  71. 

1.  SCENEDESMUS  (Fig.  79). 

The  cells  are  usually  four,  attached  together  by  their 
long  sides.  The  spines  on  the  narrow  ends  of  the  two 
terminal  cells  are  curved  towards  each  other,  and  a  spine 
sometimes  grows  from  the  centre  of  one  of  the  middle 
cells.  The  plant  is  quite  common.  S.  quadricduda, 
Fig.  79. 


DESMIDS,  DIATOMS,  AND   FRESH-WATER  ALG.E.        101 

2.  PEDIASTRUM  (Fig.  80). 

The  green  cells  are  usually  so  arranged  as  to  leave 
narrow  colorless  bands  between  them,  and  occasionally, 
in  those  species  formed  of  a  great  number  of  adherent 


Fig.  79.— Scenedesmus  quadricauda.  Fig.  80.— Pediastrnm  granulatum. 

cells,  several  apparently  empty  colorless  spaces  are  scat- 
tered about  the  disk.  In  the  latter  cases  the  colorless 
marginal  teeth  are  often  very  numerous,  but  they  are 
usually  more  or  less  conspicuously  arranged  in  twos. 
In  the  species  here  figured  the  marginal  teeth  are  gener- 
ally twelve  in  number.  P.  granulatum^  Fig.  80. 

3.  VOLVOX. 

A  small  sphere  continually  in  movement,  rolling 
through  the  water  in  a  very  graceful  manner,  its  sur- 
face studded  with  green  points.  Under  a  low  power  it 
seems  like  a  hollow  globe,  and  the  cause  of  the  mo- 
tion is  a  mystery ;  but  the  \  inch  objective,  when  the 
Volvox  moves  slowly  or  rests,  shows  that  each  green 
point  bears  two  fine  cilia  or  little  hairs  continually  vi- 
brating and  lashing  the  water.  It  is  from  their  vibra- 
tions that  the  Yolvox  receives  its  rolling  motion.  The 
deep  green  balls  often  seen  within  the  globe  are  young 
plants  in  different  stages  of  development.  When  ma- 
tured the  mother-globe  is  broken  and  the  young  plants 


102  MICROSCOPY  FOR  BEGINNERS. 

float  out  and  roll  away  through  the  water,  revolving  as 
they  are  often  seen  to  do  even  before  leaving  the  parent. 
The  water  in  some  localities  is,  in  June,  so  filled  with 
these  rolling  globes  that  it  is  colored  green  by  them, 
and  when  the  collecting-bottle  is  held  against  the  light 
they  become  visible  to  a  sharp  eye  as  small  pale-green 
spheres.  The  diameter  of  a  full-grown  plant  is  about 
one-fiftieth  of  an  inch.  V.  ylobdtor. 

4.  HYDKODICTYON  (Fig.  81). 

A  yellowish-green  scum  is  sometimes  seen  on  the  wa- 
ter, which,  when  spread  out  over  the  fingers,  proves  to 
be  a  net  of  delicate  green 
meshes.  It  may  grow  to 
ten  or  twelve  inches  in 
length,  and  form  floating 
masses  several  inches  in 
thickness.  The  nets  are 
composed  of  narrow  short 
cylindrical  cells.  Under  a 
low  power  they  'are  re- 
markably beautiful.  The 

Fig.  81.— Hydrodictyon  ntricnlfitnra. 

figure  shows  a  part  of  a 
net.     II.  utriculdtum,  Tig.  81. 

The  masses  which  the  Algae  form  are  usually  com- 
posed of  great  numbers  of  long  threads,  commonly 
called  filaments,  and  matted  together,  probably  by  their 
rapid  growth,  among  other  causes.  Each  filament  is 


DESMIDS,  DIATOMS,  AND  FKESH-WATER  ALG.E.      103 

built  up  of  many  cells  attached  to  each  other  by  their 
narrow  ends,  the  single  filament  being  considered  a  sin- 
gle and  entire  plant.  They  have  no  roots,  although 
they  may  fasten  themselves  by  one  end  to  submerged 
objects.  Some  are  simple,  straight,  or  curved  cellular 
threads ;  some  give  off  branches  which  generally  resem- 
ble the  main  plant  or  stem.  Their  color  is  usually 
some  shade  of  green,  although  a  few  purplish  and 
brownish  ones  are  known.  The  following  is  a  key  to 
those  genera  referred  to  in  this  book. 

Key  to  Genera,  of  Fresh-water  Algce. 

1.  Color  brownish-green,  bluish,  or  olive  (a). 

2.  Color  pure  green  (d). 

a.  Filaments  branched  (J). 

a.  Filaments  not  branched  (c). 

1).  Branches  with  many,  whorled,  moniliform  threads ; 

plant  slippery.     Batrachospermum,  1. 
c.  Moniliform,  with  larger  scattered  spherical  cells. 

Anabcena,  2. 

c.  Not  moniliform  ;  bluish  green ;  twisting,  bending, 

gliding.     Oscilldria,  3. 

d.  Green  color  in  one  or  more  spiral  bands  in  each 

cell.     Spirogyra,  4. 

d.  Green  color  in  two  star-shaped  masses  in  each  cell. 
Zygnema,  5. 

d.  Green  color  not  in  patterns  (e). 

e.  Terminal  cells  with  a  colorless,  hair-like  bristle  (/*). 
e.  Terminal  cells  without  a  bristle.     Vaucheria,  6. 


104  MICROSCOPY  FOR  BEGINNERS. 

f.  Forming  small   green,  visible,  jelly -like   masses. 
Chcetophora,  7. 

f.  Not  forming  jelly-like  masses  (g). 

g.  Cells  of  the  branches  green,  those   of  the   stem 

larger,  with  a  transverse  green  band.     Drapar- 
ndldia,  8. 

g.  Cells  of  branches  and  stem  green ;  bristles  with  a 
swollen  base.     Bulbochcete,  9. 

1.  BATRACHOSPERMUM  (Fig.  82). 

The  plant  often  grows  abundantly,  attached  to  sub- 
merged objects,  in  springs,  ditches,  and  ponds.  It  varies 
in  length  from  an  inch  or  less  to  one  or  two  feet,  and  in 
color  it  may  be  bluish-green,  brownish,  or  purplish.  It  is 
covered  with  a  mucous  substance  that  makes  it  very  slip- 
pery and  difficult  to  handle.  It  is  much  branched,  and 
the  branches  bear  many  short  threads  in 
whorls,  each  thread  plentifully  beaded. 
The  whorls  are  often  so  close  together 
that  the  entire  plant  as  it  floats  beneatli 
the  water  seems  to  be  a  string  of  little 
balls.  Under  the  microscope  each  mo- 
niliform  thread  is  often  seen  to  be  ter- 
minated by  a  colorless  hair-like  bristle. 

Fig.  82.— Batracho- 

epfanuin  moniii-   This,  however,  is   not    always    present. 

forme.  'With  a  high   power  the    ends    of  the 

beaded  filaments  seem  to  run  down  the  main  stem  in 
long,  narrow,  almost  colorless  cells.     J3.  moni 
Fig.  82. 


DESMIDS,  DIATOMS,  AND   FRESH-WATER  ALG^.       105 
» 

2.  ANAB.ENA  (Fig.  83). 

Filaments  moniliform,  freely  floating,  the  cells  spheri- 
cal, the  larger  scattered  ones  globular,  yellowish.     The 
filaments  are  often  curved,  and  sur- 
rounded by  a  delicate  mucous  mate- 
Fig.  83.-Anab.ma.          rjal>     ^^  &TQ  geveral  species  which 

closely  resemble  each  other  (Fig.  83). 

3.  OSCILLARIA  (Fig.  84). 

These  plants  are  found  almost  everywhere  in  the  wa- 
ter. They  often  form  thick  floating  mats  of  a  dark 
purplish  almost  blackish  color,  or  they  are  entangled 
among  other  plants  in  a  dark  green  film.  Under  the 
microscope  they  consist  of  filaments  composed  of  very 
many  short  cells  that  vary  a  good  deal  in  width  accord- 
ing to  the  species,  of  which  there  are  several.  They 
can  usually  be  known  by  the  bluish-green  color  and 
their  characteristic  motions.  Some  are  like  straight 
rods  of  cells  bending  slowly  from  side  to  side ;  others 
twist  and  writhe  and  coil  them- 
selves into  circles,  only  to  slowly 
uncoil  and  repeat  the  move- 
ments.  Some  glide  slowly  for- 
ward,  the  tip  end  gradually  bend- 
ing and  curving.  The  move- 
ments,  when  the  plants  are  in  a  healthy  condition,  are 
incessant.  The  beginner  need  never  be  at  a  loss  to  rec- 
ognize one  of  the  several  species  of  Oscillaria.  Three 
forms  are  shown  in  the  figure.  (Fig.  84.) 


106 


MICROSCOPY  FOR  BEGINNERS. 


Fig.  85.—  Spirogyra. 


4.  SPIROGYKA  (Figs.  85,  86). 

The  SpirogyrcB  are  easily  recognized  by  the  beautiful 
spiral  bands  of  green  within  each  cell,  as  shown  in  Fig. 
85.  There  may  be  one,  two,  or  several  of  these  spirals 

winding  around  the 

cell -wall,  the  num- 
ber helping  to  de- 
termine the  species, 
of  which  there  are  many.  The  plants  usually  grow  iu 
masses,  and  especially  form  those  soft  green  clouds  ap- 
parently floating  in  the  water.  They  are  often  attached 
to  submerged  objects,  but  almost  as  often  free. 

Their  manner  of  producing  spores  is  remarkable,  but 
not  confined  to  them,  as  other  Algae  have  a  similar 
method.  The  cells  of  two  filaments  lying  side  by  side 
begin,  usually  at  the  same  time,  to  throw  out  from  those 
sides  nearest  each  other  a  narrow  tube. 
These  tubes  meet  and  grow  together,  so 
that  the  two  filaments  soon  resemble  a  lad- 
der, the  original  filaments  forming  the 
sides,  the  tubes  being  the  rounds.  The 
coloring  matter  then  falls  away  from  the 
cell-walls,  and  the  entire  contents  of  the 
cells  of  one  filament  pass  through  the  rungs 
of  this  living  ladder  into  the  opposite 
cells,  where  the  contents  of  both  mingle. 
From  this  mixture  the  spore  is  formed, 
one  in  each  cell,  and  is,  when  ripe,  oval  and  dark 
brown.  This  conjugation,  as  it  is  called,  and  the  result- 


DESMIDS,  DIATOMS,  AND  FRESH-WATER  ALG.E.      107 

ing  spores  are  shown  in  Fig.  86.     The  plants  are  often 
found  in  this  condition  in  June  and  July. 

5.  ZYGNEMA  (Fig.  87). 

This  usually  floats  unattached.     The  cells  are  rather 
wide  and  short,  the  inter- 
nal stellate  masses  being  a 
deep  green  in  color.     The 

formation  of  the  spores  re- 
Fig.  ST.-Zygneraa  insigne.. 

sembles  that  of  Spirogyra. 

It  is  found  in  conjugation  in  April.     Z.  insigne,  Fig.  87. 

6.  VAUCHERIA  (Fig.  88). 

A  deep  green  mat  growing  on  the  mud  in  shallow 
water,  and  resembling  felt  both  to  touch  and  sight,  will 
usually  prove  to  be  Vaucheria.  The  filaments  are  very 
long,  with  few  branches.  The  green  matter  is  diffused 
over  the  cell- wall,  and  when  the  latter  is  broken,  flows 
out  and  often  forms  green  globules.  The  spores  are 
produced  in  two  ways,  both  of  which  the  beginner  will 
see,  as  they  are  not  rare  early  in  the  season.  In  one 
the  end  of  a  filament  enlarges  and  becomes  club-shaped, 
while  a  partition  grows  across  it  near  the  handle  of  the 
club.  The  contents  of  this  new  cell  become  very  dark, 
opaque,  and  hardened.  The  free  end  of  the  cell  then 
breaks,  and  the  spore  slowly  passes  out,  being  squeezed 
into  an  hour-glass  shape  as  it  does  so.  No  sooner  is  it 
free  than  it  is  off  like  a  flash,  being  covered  by  cilia. 
But  it  soon  settles  down,  and  finally  develops  into  a  fil- 


108  MICROSCOPY  FOB  BEGINNERS. 

amcnt  like  the  parent.  In  the  other  method  the  -fila- 
ment produces  from  the  side,  as  shown  in  Fig.  88,  a 
small  oval  cell,  and  near 
it  a  narrow  curved  or 
coiled  tube.  Presently 
the  free  ends  of  each  of 
these  cells  open,  and  the 
contents  of  the  tube  pass 
into  the  oval  cell,  in 
which  a  spore  without 
cilia  is  finally  formed. 

Fis.  S3.— Vancheria. 

This  spore  is  said  to  fall 

in  the  mud  and  to  remain  unchanged  for  many  months, 
sometimes  all  winter,  but  at  last  developing  into  another 
Yaucheria.  In  some  of  the  species  the  oval  cells  are 
several  in  a  cluster,  and  the  whole,  with  the  coiled  tube, 
is  raised  above  the  filament  on  the  end  of  a  short  stem. 

7.  CH^ETOPHOR.V  (Fig.  89). 

The  light  green  jelly-like  masses  into  which  this  Alga 
grows  are  found  attached  to  submerged  leaves  of  grass, 
twigs,  or  other  small  objects.  They  are  often  almost 
spherical,  varying  in  size  from  that  of  a  pin-head  to  that 
of  a  marble.  The  surface  is  smooth,  and  so  slippery  that 
to  pick  up  one  of  these  Chatfdphora  jellies  is  next  to  im- 
possible. The  plant  within  the  jelly  is  formed  of  fine 
branching  filaments  usually  radiating  in  all  directions 
from  a  common  centre,  the  branches  being  shorter  and 
most  numerous  near  the  surface  of  the  gelatinous  mass, 


DESMIDS,  DIATOMS,  AND  FRESH-WATER  ALG^E.      109 

their  ends  bearing  a  fine,  colorless  hair  or  bristle.     Tin- 
der a  low -power  objective  the  plant,  if  carefully  flat- 


rig.  89.— Chsetophora  elegans. 


tened  out,  is  very  beautiful, 
gant."     Ch.  elegans,  Fig.  89. 


It  is  justly  named  "  ele- 


8.  DRAPAUNALDIA  (Fig.  90). 

There  need  be  no  trouble  in  recognizing  this  Alga. 
It  grows  attached  to  many  objects,  the  fine  branches 
giving  it  a  delicate  feathery  appearance  to  the  naked 
eye.  Under  the  microscope  it  is  seen  to  be  much 
branched,  the  branches  being  arranged  in  clusters,  and 
formed  of  cells  smaller  than  those  of  the  main  stem,  and 
filled  with  chlorophyl,  while  each  terminal  cell  is  ended 
by  a  long,  colorless  hair.  The  cells  of  the  stem  are  but 
little  longer  than  wide,  and  are  colorless  except  for  a 
narrow,  light  green  chlorophyl  band  surrounding  the 
centre.  D.  glomerate^  Fig.  90. 


110  MICROSCOPY  FOR  BEGINNERS. 


Fig.  90.— Draparnaldia  glomerata. 

9.  BULBOCH^TE  (Fig.  91). 

This  genus  can  always  be  known  by  the  swollen  or 
bulbous  bases  of  the  long  hairs  that  tip  many  of  the 
.cells.  It  grows  on  larger  Algae,  or  on  the  leaflets  of 
Ceratophyllum  or  other  aquatic  plants  (Fig.  91). 


Fig.  91.— Bulbocbrete. 


RHIZOPODS.  Ill 


CHAPTER  IV. 

KHIZOPODS. 

THE  Khizopods  are  the  lowest  animals  in  the  scale  of 
life.  Scarcely  more  than  a  drop  of  jelly-like  protoplasm, 
the  lowest  of  these  lowly  creatures  live,  move,  eat,  and 
multiply.  Some  are  so  far  down  in  the  scale  that  they 
are  actually  only  a  particle  of  soft  and  unprotected 
protoplasm,  moving,  like  the  common  Amoeba,  which  is 
one  of  the  Rhizopods,  by  protruding  long,  thread-like 
projections  of  its  own  substance  from  any  part  of  its 
body,  and  withdrawing  them  again  into  its  substance, 
where  they  entirely  disappear.  These  protruded  parts, 
by  means  of  which  the  creatures  move  and  capture  their 
food,  are  called  pseudopodia,  from  two  Greek  words, 
meaning  false  feet.  And  since  they  often  extend  to 
long  distances  from  the  body  of  the  animal,  dividing 
and  branching  somewhat  after  the  manner  of  roots, 
the  group  of  lowly  animals  producing  these  pseudo- 
podia  is  named  the  Rhizopods,  or  root-footed,  a  word 
also  from  the  Greek. 

The  Amo3ba,  and  those  Rhizopods  nearest  to  it  in 
structure,  are  formed  of  naked  protoplasm;  they  are 
simply  a  drop  of  living  jelly.  But  some  higher  in  the 
same  group  secrete  or  build  around  their  soft  bodies  a 
protective  shell,  often  of  exquisite  form  and  remarkable 


112  MICROSCOPY  FOR  BEGINNERS. 

construction.  Thus  the  members  of  one  genus,  Difflu- 
gia,  build  themselves  shells  of  sand  grains  cemented 
together  with  the  most  perfect  regularity,  every  grain 
exactly  fitting  to  its  place.  Yet,  when  the  young  Dif- 
flugia  happens  to  be  where  suitable  sand  is  scarce,  it 
will  build  its  shell  of  diatoms,  often  using  those  that 
are  longer  than  the  completed  covering,  attaching  them 
lengthwise,  side  by  side,  and  parallel  to  each  other.  An- 
other genus,  Arcella,  secretes  from  its  body  a  brown 
shell  of  delicate  membrane  which,  with  a  high  power, 
is  seen  to  be  formed  in  minute  hexagons.  And  still 
another,  Clathrulina,  the  most  beautiful  of  all  the  fresh- 
water Ehizopods,  lifts  itself  on  a  long  stem,  and  there 
surrounds  its  body  by  a  hollow  latticed  sphere,  and 
through  the  openings  in  the  walls  extends  its  pseudo- 
podal  rays  in  search  of  food. 

In  the  unprotected  forms — those  without  a  shell — the 
pseudopodia  are  protruded  from  any  part  of  the  body ; 
in  those  preparing  shells  they  are  protruded  from  that 
portion  of  the  body  immediately  in  contact  with  the 
mouth  of  the  shell,  through  which  they  often  extend  for 
a  long  distance  as  very  fine,  branching  threads.  "With  a 
few  exceptions  the  bodies  of  the  Rhizopods  are  colorless ; 
in  those  exceptions  the  coloration  is  usually  due  to  the 
presence  of  colored  food,  and  so  is  diffused  throughout 
the  entire  protoplasm,  or  it  is  confined  to  the  parts  near 
the  surface,  the  central  portion  being  nearly  colorless. 
The  pseudopodia  are  never  colored. 

Not  only  do  the  Rhizopods  move  by  means  of  these 


RHIZOPODS.  113 

"  false  feet,"  but  they  capture  food  with  them,  consum- 
ing both  plants  and  animals.  Diatoms,  Desmids,  Infu- 
soria (Chapter  V.),  Eotifers  (Chapter  VIII.),  almost 
any  living  thing  small  enough  to  be  seized,  is  accepta- 
ble. When  a  desirable  morsel  is  found,  the  end  of  the 
pseudopodium  touching  it  usually  expands,  and  a  wave 
of  the  body  substance  flows  along  it  until  the  object  is 
surrounded,  like  an  island  of  food  in  a  sea  of  proto- 
plasm. The  whole  broadened  pseudopodium  is  then 
withdrawn  into  the  body,  carrying  the  food  with  it ;  or, 
if  the  captured  object  is  unusually  large,  or  if  it  strug- 
gles a  good  deal,  several  pseudopodia  may  come  to  the 
assistance  of  the  first,  or  a  great  wave-like  outflow  from 
the  body  may  envelop  both  pseudopodia  and  food. 

These  curious  animals  have  no  distinct  mouth  and  no 
distinct  stomach.  The  mouth  in  the  shell-less  ones  is 
formed  at  any  point  on  the  surface  wherever  the  creat- 
ure chooses  to  open  itself  and  take  in  the  food  parti- 
cle; and  the  stomach  is  in  any  part  of  the  internal 
substance ;  the  food  is  digested  wherever  it  may  hap- 
pen to  enter  and  remain.  They  have  no  eyes,  yet  they 
seem  to  direct  their  course  and  avoid  unpleasant  or  in- 
jurious obstacles.  They  have  no  nerves,  yet  when  dis- 
turbed they  contract  into  a  small  ball-like  mass,  or  with- 
draw themselves  into  their  shell.  They  also  appear  to 
feel  some  sort  of  sensation  of  hunger,  for  they  are  often 
seen  to  take  food,  and  they  select  what  they  like. 

They  are  very  numerous  and  common.  They  are 
to  be  found  in  any  shallow  pond,  or  pool,  or  body  of 


114  MICROSCOPY  FOR  BEGINNERS. 

still  water.  They  glide  among  aquatic  plants  and  Algae, 
especially  on  the  lower  surface  of  water-lily  leaves,  and 
among  Myriophyllum  and  Ceratoph}7llum.  Sphagnum 
moss  is  sure  to  contain  them  in  abundance,  as  has  al- 
ready been  stated  on  page  61.  But  the  mud  is  an  ac- 
cessible and  fruitful  source  of  supply.  To  obtain  them, 
gently  scrape  with  a  big  iron  spoon  or  the  edge  of  a  tin 
dipper  the  surface  of  the  ooze  from  the  mud  in  shal- 
low ponds,  and  transfer  it  to  the  collecting-bottle.  Let 
the  muddy  mixture  stand  for  a  few  minutes  until  the 
Rhizopods  settle  towards  the  bottom,  and  carefully  pour 
off  some  of  the  water,  adding  more  ooze  if  desired. 
Pour  the  mud  and  water  into  saucers,  and  set  them  near 
the  window,  when  the  Rhizopods  will  make  their  way 
to  the  surface,  and  may  be  removed  by  the  dipping- 
tube.  Do  not  place  the  saucers  in  the  sunlight ;  Rhiz- 
opods  prefer  a  little  shade.  They  are  invisible,  conse- 
quently the  collector  must  collect  on  faith,  as  he  must 
usually  do  when  out  on  a  microscopical  fishing  tour. 
But  he  will  seldom  be  disappointed  if  he  gathers  the 
surface  ooze  from  the  edges  of  somewhat  shady  ponds, 
and  avoids  those  places  long  exposed  to  the  sun,  and 
never  sinks  the  dipper  into  the  thick  black  mud,  which 
contains  no  animal  life  of  any  kind. 

They  are  small  and  easily  overlooked  in  the  field  of 
the  microscope,  but  when  one  of  the  unprotected  forms 
and  a  single  shell-bearing  Rhizopod  is  recognized,  the 
beginner  will  never  again  overlook  any  of  them  in  the 
material  on  his  slide.  The  Amoeba  will  probably  be 


RHIZOPODS.  115 

the  first  seen,  as  a  colorless,  jelly-like  body,  very  soft, 
and  changeable  in  shape,  slowly  moving  forward  and 
suddenly  altering  its  course  and  extending  itself  in  nu- 
merous long,  blunt,  finger-like  pseudopodia,  lengthening 
or  shortening  at  the  creature's  will.  Or  he  may  see 
a  small  pear-shaped  collection  of  sand-grains  slowly  mov- 
ing about  the  slide,  apparently  without  a  cause,  but  a 
careful  examination  of  the  narrow  or  stem  end  of  the 
pear  will  show  the  long,  fine,  and  colorless  pseudopodia 
issuing  from  the  mouth,  and  he  will  know  it  to  be  a 
Rhizopod.  After  he  has  recognized  a  living  shell  he 
will  have  no  trouble  thereafter  in  knowing  a  dead  one, 
and  by  referring  to  the  following  Key  he  will  be  able 
to  learn  its  name,  unless  it  is  a  very  uncommon  species. 

Key  to  Genera  of  Rhizopods. 

1.  Body  without  a  shell  (a). 

2.  Body  with  a  shell  (e). 

a.  "Without  fine,  hair -like  rays;  pseudopodia  thick 

and  blunt  (b}. 
a.  With  fine,  hair-like  rays  on  all  parts  of  the  body 

w- 

I).  Body  colorless,  very  changeable  in  shape.  Amoe- 
ba, 1. 

c.  Body  orange  or  brick -red,  with  pin -like  rays. 
Vampyrella,  2. 

c.  Body  colorless  or  greenish  (d). 

d.  Eays  stiff,  forked  at  the  ends ;  body  often  green. 

Acanthocystis,  3. 
6* 


110  MICROSCOPY  FOR  BEGINNERS. 

d.  Kays  flexible,  not  forked.       Actinophrys,  4,  or 

Actinosphcerium,  5. 

e.  Shell  formed  apparently  of  sand-grains  (/). 
e.  Shell  not  formed  of  sand-grains  (g). 

e.  Shell  a  latticed  globe  on  a  long  stem.     Clathru- 

lina,  12. 

/.  Not  inclined ;  pear-shaped,  or  globular  with  spines 
at  the  summit.  Diffiugia,  6. 

f.  Inclined;    circular  or  oblong,   thicker   and   with 

spines  at  the  rear.     Centropyxis,  7. 

g.  Shell  brown  (A). 

g.  Shell  colorless,  ovoid,  not  curved  (*). 

g.  Shell  often  yellowish,  ovoid,  curved  (retort  shaped), 
mouth  circular.  Cyphoderia,  11. 

h.  Circular,  with  or  without  marginal  teeth.  Ar- 
cella,  8. 

i.  Mouth  smooth,  circular;  shell  inclined,  without 
spines.  Trinema,  9. 

i.  Mouth  serrated  ;  shell  not  inclined,  formed  of  hex- 
agonal plates ;  often  spinous.  Euglypha,  10. 

1.  AMCEBA  (Fig.  92). 

There  is  hardly  a  living  animal  so  soft  and  changea- 
ble in  shape  as  this.  It  may  not  retain  the  same  form 
for  a  second  at  a  time.  The  soft  body  protrudes  thick, 
blunt,  finger-like  pseudopodia  from  any  part  of  its  sur- 
face, but  usually  from  the  front  margin,  or  that  edge  at 
the  forward  part  of  the  moving  creature.  The  front 
may,  with  scarcely  a  warning,  become  the  rear  as  the 


RHIZOPODS.  117 

animal  changes  its  course,  by  emitting  pseudopodia  from 
gome  other  portion,  travelling  off  in  the  direction  tow- 
ards which  they  extend.  The  semi-fluid  contents  of  the 
body  are  colorless,  unless  tinged  by  the  food  or  by  the 
presence  of  numerous  dark  particles.  The  movements 
are  sometimes  quite  rapid,  the  Amoeba  extending  its 
pseudopodia,  keeping  them  extended  in  advance,  and  glid- 
ing along  as  though  the  body  were  formed  of  the  white 
of  egg.  In  the  figure  it  is  shown  with  many  short 
pseudopodia,  as  it  often  appears  immediately  after  it  is 
placed  on  the  slide,  and  before  it  has  learned  where  it  is, 
and  has  prepared  to  move  in  some  definite  direction. 
The  posterior  extremity,  when  the  Amoeba  is  in  motion, 
may  be  entirely  smooth,  or  it  may  show  a  cluster  of  very 
short  pseudopodia,  giving  it  a  velvety  or  mulberry  ap- 
pearance. Suddenly  a  blunt,  thick  finger  projects  from 
the  part,  and  Amoeba  at  once  reverses  its  course,  the 
pseudopodia  at  the  front  being  withdrawn,  and  disappear- 
ing in  the  substance  of  the  body.  The  observer  can 
never  predict  what  an  Amoeba  will  do  next.  It  is  very 
common  in  the  ooze  of  shallow  ponds  and  on  the  leaves 
of  many  aquatic  plants.  Its  body  usually  contains  a 
number  of  diatoms,  which  form  part  of  its  favorite  food, 
and  it  is  a  strange  fact  that  the  food  is  usually  taken  by 
what,  at  the  time,  is  the  posterior  extremity.  There  are 
several  species. 

1.  Body  large,  colorless  or  blackish ;  pseudopodia  finger- 

like,  blunt.     Amosba  proteus,  Fig.  92. 

2.  Body  small,  colorless,  rather  sluggish ;  often  floating 


118 


MICROSCOPY  FOR  BEGINNERS. 


freely,  and  star-shaped,  with  several  conical,  acute, 
straight,  or   curved   pseudopodia 
radiating  from  the  spherical  cen- 
tral body.      The   form    changes 
very  slowly.     A.  radiosa. 
3.  Body  irregular  in  shape;  pseudo- 
podia usually  few,  short,  thick, 
and  directed  forward ;   posterior    Fig.  92.  —  Amceba  pr6- 
portion  of  the  body  with  a  vil- 
lous  or  velvet -like  patch  of  very  short,  colorless 
pseudopodia.    A.  villosa. 

2.  VAMPYRELLA  LATERI'TIA  (Fig.  93). 
A  red  or  orange  colored,  Amoeba-like  creature  with 
this  name  is  not  uncommonly  found  in  early  spring 
among  thick  growths  of  Spirogyra,  for  which  it  has  a 
special  fondness.  It  does  not  very  quickly  nor  frequent- 
ly change  its  shape,  yet  its  movements  are  quite  rapid. 
Its  pseudopodia  are  colorless  and  transparent,  being 
formed  by  a  short  outward  flow  of  the 
colorless  central  body  substance,  the  red 
color  being  confined  chiefly  to  the  sur- 
face. It  also  has  .short,  fine  rays  like 
threads,  and  many  pin-like  projections, 
Fig.  93.-varapyreiia  by  which,  in  connection  with  its  color, 
Vampyrella  may  be  easily  recognized. 
These  pin-like  rays  consist  of  a  short,  fine  stem  with  a 
little  bulb  on  the  end,  so  that  each  looks  very  much 
like  a  pin  with  a  big  head.  They  may  appear  on  all 


RHIZOPODS.  119 

parts  of  the  body,  but  usually  they  are  on  the  rear  end 
only  when  the  animal  is  moving.  They  often  appear 
very  suddenly,  and  as  quickly  disappear. 

Yampyrella's  favorite  food  seems  to  be  the  cell  con- 
tents of  Spirogyrse.  It  selects  a  fresh  and  healthy  plant, 
and  settling  down  upon  it,  proceeds  to  perforate  the  cell- 
wall,  and  to  remove  the  color  bands  with  the  entire  cell 
contents  by  drawing  them  into  its  body,  leaving  the  cell 
quite  empty,  with  a  ragged  hole  in  the  side.  I  have  seen 
one  Vampyrella  remove  the  contents  from  seven  Spiro- 
gyra  cells  in  succession  before  its  appetite  was  satisfied. 

3.    ACANTHOCYSTIS  CH^ETOPHORA  (Fig.  94). 

Body  spherical,  soft,  usually  colored  green  by  the 
numerous  green  granules  within.  When  the  animal 
changes  its  shape,  which  it  seldom  does,  it  only  becomes 
oval  or  slightly  irregular  in  outline.  The  pseudopodia 
are  very  fine  and  hair-like,  springing  from  all  parts  of 
the  surface,  but  the  peculiarity  by  which  it  may  easily 
be  known  is  the  dense  growth  of  spines  covering  the 
entire  body,  their  ends  being  forked  or  divided  into  two 
short,  straight,  diverging  branches.  To  see  these  forked 
ends  demands  a  rather  high-power  objective,  as  they  are 
small,  butf  the  spines  themselves  are  apparent  to  a  com- 
paratively low -power.  They  seem  not  very  securely 
fastened  to  the  animal ;  some  of  them  quite  often  be- 
come loosened  and  drop  off,  especially  if  the  Rhizopod 
is  not  in  a  healthy  condition. 

When  food  is  to  be  taken  into  the  body,  a  part  of  the 


120  MICROSCOPY  FOR  BEGINNERS. 

surface  with  the  adherent  spines  is  lifted  up,  carrying 
the  spines  to  one  side,  and  a  wave  of 
protoplasm,  the  body  substance,  flows 
out  to  receive  and  surround  the  food 
brought  down  by  the  pseudopodia.  It 
is  drawn  into  the  body,  the  surface 
closes,  and  the  spines  again  cover  the 

sPot  Tllis  may  happen  at  any  Part 

of  the  surface. 
Acantfwcystis  is  often  found  among  the  leaflets  of 
Myriophyllum,  the  roots  of  Lemna,  or  floating  freely  in 
quiet  water.     It  is  rarely  found  in  the  mud. 

4.  ACTINOPHRYS  SOL  (Fig.  95). 

This  is  one  of  the  commonest  of  aquatic  microscopic 
animals.  It  may  be  found  floating  in  every  quiet  pond 
or  pool,  or  swimming  among  the  leaflets  of  nearly  every 
gathering  of  water-weeds.  Its  body  is  usually  colorless 
and  almost  transparent,  seeming  to  be  formed  of  a  col- 
lection of  small  bubbles,  so  that  it  has  a  foamy  appear- 
ance. It  bristles  with  numerous  long,  fine  rays  spring- 
ing from  the  whole  surface.  It  moves  in  a  slow,  gliding 
way  that  has  not  been  satisfactorily  explained,  but  which 
can  hardly  be  produced  by  the  hair-like  rays,  for  they 
are  motionless,  and  apparently  used  only  for  capturing 
food.  Yet  it  slowly  floats  across  the  field  of  view,  sel- 
dom changing  its  shape;  or  it  remains  suspended  al- 
most stationary  in  the  water  with  all  its  rays  extended, 
and  so  resembling  the  pictures  of  the  sun  in  an  almanac 


KHIZOPODS.  121 

that  it  has  received  the  name  of  the  "  sun  animalcule." 
The  rays  are  seldom  entirely  with- 
drawn. 

It  feeds  on  smaller  animals  and 
the  spores  of  Algae.  When  an 
animalcule  comes  in  contact  with 
the  rays  it  seems  to  lose  some  of 
its  power  of  motion.  It  appears  to 

,  ,•    -II  i  ITT  Fig.  95.— Actiuophrys  sol. 

become  partially  paralyzed,  gliding 
down  the  ray,  often  surrounded  by  a  small  drop  of  pro- 
toplasm, until  it  nears  the  body,  when  a  larger  wave 
flows  out  and  receives  it.  The  little  masses  of  digest- 
ing food  can  be  seen  inside  the  body,  where  the  green 
coloring  usually  turns  to  brown. 

5.  ACTINOSPH^EUIUM:  EICHHORNII  (Fig.  96). 
At  first  the  beginner  will  confound  this  Rhizopod  with 
Actinophrys  sol,  which  it  resembles  in  appearance  when 
seen  with  a  low-power  objective.  It  is  larger  than  the 
"sun  animalcule,"  but  this  is  a  distinction  of  no  value 
unless  the  observer  has  happened  to  find  Actinophrys 
first,  and  to  have  become  familiar  with  its  appearance 
and  structure.  In  Actinosphcerium,  however,  the  ray- 
like  pseudopodia  are  quite  large  and  coarse,  and  they  ta- 
per to  their  free  end  from  a  thickened  base  at  the  sur- 
face of  the  body.  The  body  itself,  as  the  student  will 
notice  if  he  uses  a  %  or  ^  inch  objective,  is  formed  of 
an  external  layer  of  large  vesicles  or  bubbles,  and  a 
central  mass  of  smaller  bubbles.  In  this  bubble -like 


122  MICROSCOPY  FOR  BEGINNERS. 

structure  it  also  resembles  Actinophrys,  but  it  seems 
less  like  a  drop  of  froth,  for  the  bubbles  are  larger,  and 
the  two  distinct  layers  of  two  different  sizes  at  once 
show  that  the  Khizopod  is 
Actinosphserium.  But  there 
is  another  and  more  impor- 
tant difference,  which  the  be- 
ginner will  not  observe  un- 
less he  searches  for  it  with 
a  high-power  (^  or  £)  object- 
ive. Each  ray  has  a  thread 

Fig.  96 Actiuosphserium  Eichh6rnii. 

or  fine  rod  running  length- 
wise through  its  middle,  and  differing  slightly  in  color 
from  the  softer  part  of  the  ray.  This  rod  begins  within 
the  body  below  the  outer  layer  of  larger  bubbles,  pass- 
ing between  them  and  extending  almost  to  the  end  of 
the  pseudopodal  rays,  which  are  seldom  entirely  with- 
drawn into  the  body. 

Actinosphaerium  is  sluggish,  moving  slowly  and  often 
remaining  motionless  for  a  long  time  in  one  spot.  It  is 
frequently  found  in  company  with  Actinoplirys,  among 
Lemna  and  other  aquatic  plants. 

It  feeds  on  other  animals  as  well  as  plants,  taking 
larger  victims  than  the  "sun  animalcule."  The  Roti- 
fers (Chapter  VIII.)  seem  its  favorite  food.  A  free 
swimming  animalcule  or  Rotifer  coming  in  contact  with 
the  long  rays  seems,  as  with  Actinoplirys,  to  become  in- 
capable of  escape  ;  it  is  then  slowly  drawn  into  the  body 
and  digested. 


RHIZOPODS.  123 

6.  DIFFLUGIA  (Figs.  97,  98). 

Shell  brown,  pear-shaped,  ovoid  or  nearly  spherical, 
and  formed  of  angular  sand -grains  cemented  togeth- 
er. The  upper  part,  the  summit,  may  be  rounded,  and 
roughened  only  by  the  edges  of  the  sand -grains,  or 
rounded  and  bearing  several  pointed  spines  also  form- 
ed of  sand.  The  lower  part  may  be  prolonged  as  a 
short  neck,  at  the  end  of  which  is  the  mouth  for  the 
passage  of  the  pseudopodia,  or  the  shell  may  have  no 
part  resembling  a  neck.  The  animal  which  builds 
this  protective  case  lives  inside  of  it,  and  is  a  little 
mass  of  colorless,  or  sometimes  greenish,  protoplasm, 
somewhat  resembling  an  Amoeba,  and  almost  entire- 
ly filling  the  cavity  of  the  shell.  The  mouth  is  circu- 
lar, and  may  be  either  smooth  or  with  several  rounded 
teeth  or  lobes  on  its  inner  edge.  No  .part  of  the  ani- 
mal in  any  of  the  shell-bearing  forms,  except  the  pseu- 
dopodia, ever  passes  through  the  mouth.  When  the 
shell  is  made  the  animal  never  leaves  it,  unless  it  is 
broken  by  the  cover-glass ;  then  it  will  at  times  creep 
out  and  die. 

The  pseudopodia  are  blunt  and  colorless.  They  drag 
the  shell  about  with  the  mouth  downward,  and  capture 
food  as  in  the  naked  Khizopods.  When  they  are  with- 
drawn, the  shell  appears  like  a  dead  thing,  and  may  roll 
about  the  slide  at  the  will  of  the  observer  or  the  mercy 
of  the  currents.  But  often  while  the  student  is  looking 
at  an  apparently  dead  shell  of  sand,  a  blunt  little  color- 
less wave  issues  from  the  mouth,  lengthens  and  narrows, 


124  MICROSCOPY  FOR  BEGINNERS. 

is  followed  by  another  and  another,  until  the  shell  is 
raised  and  moved  slowly  away. 

There  are  several  species  of  the  genus  Difflugia,  of 
which  the  following  are  about  the  commonest.  They 
are  found  abundantly  in  the  mud  and  among  Sphagnum. 

1.  Shell  pear-shaped  (Fig.  97),  without  spines,  although 

the  summit  may  be  prolonged  into  one  or  two 
points ;  usually  formed  of  sand-grains, 
sometimes  with  adherent  diatoms ;  oc- 
casionally formed  entirely  of  diatoms ; 
mouth  at  the  narrow  end,  circular, 
smooth,  without  teeth  or  lobes.  The 
body  within  the  shell  is  usually  green, 
sometimes  colorless ;  pseudopodia  col- 
orless, thick,  blunt.  It  is  almost  as 
fond  of  the  cell  contents  of  Spirogyra 
as  is  Yampyrella,  and  obtains  them  in  a  similar  way ; 
but  instead  of  appearing  to  suck  them  out  of  the 
cell,  Difflugia  jpyriformis  pierces  the  wall,  inserts 
its  pseudopodia,  with  them  surrounding  the  color 
bands  and  other  cell  contents,  lifts  the  whole  out 
and  passes  it  into  the  body  within  the  shell.  I  have 
seen  a  single  Difflugia  empty  four  Spirogyra  cells 
in  succession.  This  species  is  common.  Difflugia 
pyriformis,  Fig.  97. 

2.  Shell  nearly  spherical,  with  from  one  to  twelve,  usu- 

ally three  or  seven,  pointed  spines  arranged  in  a 
circle  around  the  upper  part,  and  formed  of  sand- 
grains.  These  spines  are  hollow,  and  communicate 


RHIZOPODS.  125 

with  the  cavity  of  the  shell,  but  the  animal  proba- 
bly builds  them  for  ornament,  as  it  does  not  seem 
to  use  them.  The  mouth  of  the  shell  occupies  the 
end  opposite  to  the  spine  -  bearing  summit,  and 
when  the  shell  is  turned  over  so  that  this  opening 
is  directed  upward,  it  will  be  seen  to  be  lobed  or 
scalloped,  the  lobes  varying  from  six  to  sixteen, 
being  usually  about  twelve.  They  may  in  some 
forms  be  rather  sharp -pointed,  almost  like  short 
teeth.  They  are  directed  towards  each  other  across 
the  opening.  It  is  a  difficult  matter  to  get  the 
shell  in  such  a  position  that  the 
observer  can  look  down  into  the 
mouth,  but  it  may  sometimes  be 
done  by  tapping  the  cover-glass  with 
a  needle  so  as  to  roll  the  Khizopod 
about,  and  occasionally,  by  one  of 
those  lucky  accidents  that  some- 
times  occur,  it  places  itself  in  good 
position.  The  soft  body  is  colorless  or  brownish,  and 
the  pseudopodia  are  thick,  blunt,  and  numerous.  The 
species  is  common  in  the  ooze.  D.  corona,  Fig.  98. 

3.  Shell   spherical,   without   spines ;    mouth    circular, 

smooth,  without  lobes  or  teeth.  This  species  is 
found  with  the  preceding.  D.  globulosa. 

4.  Shell  long  and  narrowly  pear-shaped,  the   summit 

prolonged  into  a  central  sharp  point ;  mouth  circu- 
lar, smooth,  without  teeth  or  lobes.  Common.  D. 
acumindta. 


126  MICROSCOPY  FOR  BEGINNERS. 

7.  CENTROPYXIS  ACULEATA  (Fig.  99). 

The  shell  of  this  Rhizopod  is  usually  formed  of  sand- 
grains,  and  is  brown  in  color,  but  sometimes  it  consists 
of  a  brown  membrane  with  scattered  adherent  sand- 
grains.  I  have  also  met  with  shells  formed  entirely  of 
small  diatoms  fitted  together  as  beautifully  and  accu- 
rately as  the  sand-grains  of  Difflugia.  These  diatom 
shells  were  found  in  an  aquarium,  and  were  probably 
built  of  these  plants  because  suitable  sand  was  not 
to  be  had.  Centropyxis,  when  seen  in  side  view,  ap- 
pears as  if  it  had  once  been  a  hemi- 
sphere with  the  mouth  near  one  side  of 
the  flat  surface,  but  that  while  it  was  soft 
the  convex  part  had  in  some  way  been 
pushed  over  towards  one  side,  thus  leav- 
ing the  shell  oblique  or  inclined,  the  back 
part  being  much  thicker  than  the  front, 
the  upper  surface  sloping  down  from  the  deeper  rear 
to  the  thin  front  margin,  the  circular  or  oval  mouth 
remaining  nearer  the  thin  border.  The  figure  shows 
the  under  part  of  a  shell,  which,  in  this  position,  ap- 
peal's almost  circular.  The  spines  on  the  thick  part  are 
usually  sharp-pointed,  and  vary  in  number  from  one  to 
nine.  The  body  of  the  animal  is  colorless,  and  the 
pseudopodia  are  blunt  and  finger-like.  This  is  the  only 
known  species.  Common. 

8.  ARCELLA  (Figs.  100,  101). 
"When  seen  from  above  or  below,  the  shell  of  Arcella, 


RHIZOPODS.  127 

seems  like  a  disk  with  a  pale  circular  spot  in  the  mid- 
dle. When  seen  in  side  view  it  has  a  flat  lower  surface 
and  a  more  or  less  strongly  convex  or  elevated  upper 
surface.  In  color  it  is  usually  some  shade  of  brown, 
but  may  be  almost  black.  In  very  young  specimens 
the  shell  is  often  nearly  colorless.  It  is  generally  trans- 
parent. The  mouth  of  the  shell,  in  the  centre  of  the 
flat  surface,  is  circular  and  smooth.  The  body  of  the 
animal  is  colorless,  and  is  attached  to  its  home  by  fine 
threads  of  its  own  substance.  There  are  several  species, 
recognizable  by  the  form  of  the  shell. 

1.  Margin  of  the  shell  smoothly  circular.      Common 

everywhere.     Arcella,  vulgdris,  Fig.  100. 

2.  Margin  of  the  shell  with  several  teeth,  so  that  it  re- 

sembles, when  seen  from  above  or  below,  a  wheel 
with  pointed  cogs.  Not  as  common  as  the  preced- 
ing. A.  dentdta,  Fig.  101. 

3.  Shell  somewhat  balloon  -  shaped  when  seen  in  side 

view ;  higher  than  wide,  the  sides  often  depressed 
in  wide  facets.  Not  rare.  A.  mitrdta. 


Fig.  101.— Arcel- 
Fig.  100.— Arcella  vulgaris.  la  dentata.  Fig.  102.— Tnuema  Suchelys. 

9.  TRINEMA  ENCHELYS  (Fig.  102). 
This  shell  is  pouch-shaped,  colorless,  small,  and  in- 


128  MICROSCOPY  FOR  BEGINNERS. 

dined,  so  that  when  in  motion  with  the  mouth  down- 
ward against  the  slide  the  rounded  summit  is  lifted 
obliquely  upward.  It  is  somewhat  narrower  at  the 
lower  part,  and  the  mouth  is  a  short  distance  within 
the  shell,  the  front  or  lower  edges  seeming  to  curve  in- 
ward to  meet  it.  The  body  of  the  animal  is  colorless. 
The  pseudopodia  are  very  fine,  thread-like,  and  few  in 
number.  The  Rhizopod  is  common  everywhere  in  wet 
places ;  it  is  also  one  of  the  smallest,  and  the  shell  is 
often  found  dead  and  empty.  The  figure  shows  it  in 
side  view.  The  aperture  of  the  shell  is  seen  to  be  bead- 
ed when  examined  with  a  high-power  objective. 

10.  ETJGLYPHA  (Fig.  103). 

The  shell  of  Euglyplia  is  ovoid,  colorless,  and  trans- 
parent. Under  a  high  power  it  is  seen  to  be  composed 
of  many  oval  or  hexagonal  plates  arranged  in  rows, 
those  towards  the  widest  part  of  the  shell  overlapping 
those  in  front.  The  mouth  is  circular  or  oval,  but  the 
projecting  points  of  the  plates  give  it  a  toothed,  saw- 
like  edge.  There  are  several  species,  but  they  all  may 
be  known  as  Euglyphae  by  this  serrated  or  saw-toothed 
mouth.  The  upper  part  and  the  borders  of  the  shell 
are  either  with  or  without  spines,  or  they  may  bear  fine 
hairs.  The  animal  itself  is  colorless,  and  almost  entire- 
ly fills  the  cavity  of  the  shell,  to  which  it  is  attached, 
apparently  by  the  summit  only.  The  pseudopodia  are 
very  delicate  and  often  branched.  The  animal  moves, 
like  all  the  shell-bearing  forms,  with  the  mouth  of  the 


RHIZOPODS.  129 

shell  against  the  slide  or  other  object  over  which  it 
creeps. 

1.  Shell  without  spines,  or  with  four  or 

six  near  the  summit  and  arranged 
in  a  circle  at  equal  distances  apart, 
pointing  upward  and  varying  some- 
what in  length.  Quite  common  in 
the  ooze  of  ponds.  Euglypha  alve-  m«.  m- 
oldta,  Fig.  103.  alveol*ta- 

2.  Shell  with  a  cluster  of  spreading  spines  springing 

from  the   centre   of   the   summit.      Common   in 
Sphagnum.    K  cristdta. 

3.  Shell  with  the  summit  and  sides  fringed  with  bris- 

tles.    Common  in  Sphagnum.     E.  cilidta. 

11.  CYPHODEKIA  AMPULLA  (Fig.  104). 
Shell  yellowish,  or  sometimes  colorless,  shaped  like  a 
chemist's  retort,  the  mouth  being  at  the  narrow,  curved 
end.  The  summit  is  rounded,  sometimes  with  a  cen- 
tral point  or  small  knob.  The  shell,  when  highly  mag- 
nified, is  seen  to  be  formed  of  minute  hexagons.  The 
animal  is,  as  usual,  colorless,  and  nearly  fills  the  semi- 
transparent  case.  The  pseudopodia  are 
numerous  and  often  forked.  When  mov- 
ing>  the  mouth  of  the  shell  is  in  contact 

deria  ampulla.         wjth    ^     object    oyer    whjcll    faQ    RhizO- 

pod  is  travelling,  and  the  body  of  the  shell  is  held 
obliquely  upward  or  almost  parallel  with  the  slide. 
The  figure  shows  an  empty  shell.  There  is  but  one 


130  MICROSCOPY  FOR  BEGINNERS. 

species,  which  is  quite  frequent  in  the  ooze  of  ditches 
and  ponds. 

12.   CLATHRULINA  ELEGANS  (Fig.  105). 
A  hollow  globe  of  silicious  lattice-work  elevated  on  a 
crystalline  stem.     Within  this  exquisite   dwelling  the 
spherical,  colorless  animal  lives,  extending  its  fine  long 
pseudopodal  rays  through  the  almost  circular  windows  in 
search  of  food.     The  stem  is  attached  to  aquatic  plants 
or  other  submerged  objects.     Cloth- 
rulma  is  the  only  fresh-water  Rhi- 
zopod  that  is  not  free  -  swimming. 
It  is  common  in  many  ponds,  at- 
tached to  the  rootlets  of  Lemna. 


In  this  small  book  it  is  only  possi- 
ble to  refer  to  a  very  few  of  the  com- 
monest of  these  beautiful  and  in- 
teresting animals,  about  whose  life 
history  very  little  is  known.  They 
PI'S.  105.— ciathrniina  eie-  form  a  department  in  which  there 
is  room  for  much  original  inves- 
tigation. Those  who  desire  to  pursue  the  subject,  or 
to  know  more  of  the  Rhizopods  than  can  be  included 
here,  would  do  well  to  refer  to  Dr.  Leidy's  "  Fresh-water 
Rhizopods  of  North  America,"  published  by  the  United 
States  Geological  Survey  of  the  Territories,  or  to  Mr. 
Romyn  Hitchcock's  "  Synopsis  of  the  Fresh-water  Rhizo- 
pods," a  useful  condensation  of  Dr.  Leidy's  splendid  work. 


INFUSORIA.  131 


CHAPTER  V. 

INFUSOKIA. 

THE  reader  probably  knows  the  Infusoria  under  the 
name  of  animalcules,  a  word  only  meaning  small  ani- 
mals, which  the  Infusoria  certainly  are.  But  a  mouse 
is  also  a  small  animal ;  so  is  a  Water-flea  (Chapter  X.) 
and  a  Rotifer  (Chapter  VIIL).  Infusorium  for  a  single 
one  of  a  group  of  certain  microscopic  creatures,  and  In- 
fusoria as  the  plural,  are  better  words  than  animalcule, 
with  no  danger  of  conveying  an  incorrect  meaning.  The 
Infusoria  were  so  named  because  they  were  first  discov- 
ered in  infusions,  that  is,  water  in  which  animal  or  vege- 
table substances  had  been  soaking  and  decaying.  Since 
that  time  the  creatures  have  been  obtained  in  great 
abundance  and  variety  in  even  the  sweetest  of  fresh  wa- 
ters, although  they  abound  in  astonishing  numbers  in 
many  infusions.  The  beginner  has  only  to  place  a  hand- 
ful of  hay  in  a  tumbler  of  water,  and  allow  it  to  soak 
for  a  week  or  two,  when  he  will  have  as  many  Infusoria 
as  he  may  want  for  examination.  They  are  also  plenti- 
ful in  every  ditch  and  pool  of  still  water.  ~No  collec- 
tion of  Algse,  aquatic  plants,  or  Rhizopods,  can  be  made 
without,  at  the  same  time,  gathering  very  many  Infusoria. 

One  of  the  best  ways  to  collect  the  little  creatures  is 
to  gather  aquatic  plants  and  Algae  without  taking  them 
7 


132  MICROSCOPY  FOR  BEGINNERS. 

from  the  water.  If  the  plants  among  which  they  con- 
ceal themselves  and  search  for  food  are  lifted  out  of  the 
pond,  the  water  running  off  washes  away  all  the  animals 
you  are  seeking.  So  take  the  water  in  the  dipper,  or 
float  the  plants  into  the  bottle,  which  should  never  be 
entirely  filled,  nor  corked  for  any  length  of  time.  The 
Infusoria  are  very  fond  of  fresh  air ;  they  rapidly  ex- 
haust the  oxygen  in  solution  in  the  water,  dying  quickly, 
and  going  to  pieces  almost  as  soon  as  dead.  Give  them 
plenty  of  air  in  the  collecting-bottle,  and  at  home  pour 
the  gathering  into  a  broad  dish  so  as  to  have  a  wide  sur- 
face exposed  to  the  atmosphere.  The  plants  as  well  as 
the  Infusoria  do  better  in  such  quarters.  They  are  also 
usually  fond  of  the  light,  and  will  soon  make  their  way 
to  the  side  of  the  vessel  nearest  the  window,  and  the 
dipping-tube  put  in  at  that  side  will  often  capture  creat- 
ures that  avoid  the  shadier  parts.  To  obtain  those  that 
are  free-swimming,  that  is,  those  that  are  never  perma- 
nently adherent  to  the  leaflets  of  plants  nor  the  fila- 
ments of  Algae,  as  many  of  the  most  interesting  are, 
they  can  be  transferred  to  the  slide  by  the  dipping-tube, 
and  the  drop  covered  by  the  thin  glass,  when  they  are 
ready  for  study.  Those  attached  to  plants  can  be  found 
only  by  cutting  off  a  small  piece  of  Myriophyllum  or 
other  water -weed  and  examining  it  under  the  micro- 
scope. In  these  cases  it  is  necessary  to  lift  the  piece  of 
weed  from  the  water,  but  it  can  be  moved  gently,  and 
at  once  placed  in  a  drop  ready  for  it  on  the  slide.  Some 
of  the  most  interesting  kinds  of  Infusoria  are  found  ad- 


INFUSORIA.  133 

herent  to  Ceratophyllum  and  other  plants  with  finely 
divided  leaves.  Every  part  should  be  searched  with  the 
microscope,  especially  the  angles  between  the  leaflets. 

The  bodies  of  the  Infusoria  are  usually  very  soft 
and  delicate.  Some  of  them  are  so  flexible  that  they 
can  double  and  twist  themselves  almost  as  well  as  a 
worm.  Others  are  hard,  and  some  are  even  covered  by 
a  transparent  case  secreted  from  their  own  body.  This 
case  is  called  a  lorica,  and  is  used  as  a  shelter  for  the 
soft  and  otherwise  defenceless  animal.  When  fright- 
ened it  quickly  withdraws  itself  to  the  bottom  of  the 
lorica,  and  remains  there  in  a  little,  almost  shapeless, 
heap,  until  the  danger  is  past.  Then  it  slowly  rises  up 
to  the  front  of  the  lorica,  protrudes  the  front  part  of 
the  body,  opens  the  organs  by  which  it  creates  currents 
in  the  water,,  and  so  fishes  for  the  food  those  currents 
bring  to  its  mouth.  These  loricae  are  usually  perma- 
nently attached  to  plants  or  other  submerged  objects. 
They  are  also  generally  transparent  and  colorless,  but 
sometimes,  as  they  become  old,  the  color  changes  to  a 
rich,  translucent  chestnut  brown.  In  other  Infusoria 
the  loricse  are  not  hard  and  transparent,  but  soft  and 
delicate.  These  are  usually  made  of  innumerable  little 
particles  of  dirt  fastened  together  by  a  sticky  substance 
secreted  from  the  animal's  body.  Almost  any  small 
particles  floating  about  and  striking  against  the  sticky 
mass  will  be  quite  sure  to  adhere,  and  so  help  build  up 
the  soft  sheath  that  serves  the  Infusorium  as  a  protect- 
ive covering,  and  sometimes  effectually  conceals  it  from 


134:  MICROSCOPY  FOR  BEGINNERS. 

the  microscopist  who  may  be  seeking  it.  But  they  are 
not  formed  entirely  by  accident.  They  are  built  chiefly 
of  those  little  particles  brought  to  the  animal  by  the 
currents  produced  by  the  organs  it  has  for  that  purpose. 
These  currents  contain  the  food  which  the  Infusorium 
cannot  go  to  seek  as  the  free-swimming  kinds  can  do, 
for  the  loricas  building  animals  are  almost  as  perma- 
nently fastened  to  their  loricse  as  is  a  snail  to  its  shell. 
Sometimes  the  Infusorium  will  leave  its  lorica  when 
the  water  has  lost  most  of  its  oxygen,  and  the  poor  thing 
is  nearly  smothered,  and  it  leaves  only  to  die.  But  it 
generally  prefers  to  die  at  home,  for  when  the  time 
comes  the  little  creature  retires  to  the  bottom  of  the 
lorica,  contracts  into  a  heap,  and  quietly  goes  to  pieces. 

There  are  also  some  that  form  loricse  and  are  still 
free  -  swimming,  carrying  the  house  about  with  them. 
They  also  retire  to  the  rear  when  frightened,  and  some 
even  have  a  little  piece  of  hard  substance  on  the  front 
of  the  body  with  which  they  plug  up  the  entrance,  and 
so  make  all  secure. 

There  are  others  that  form  a  stem  and  branches  like 
the  trunk  and  limbs  of  miniature  trees,  the  colorless 
animals  being  fastened  to  the  ends  like  so  many  leaves. 
In  some  of  these  the  animals  can  contract  themselves 
into  little  balls  when  frightened ;  in  others  the  branches 
contract  into  coils  and  pull  the  animals  away  from  harm ; 
in  still  others  the  whole  tree-like  colony,  stem,  branches, 
and  animals,  contract  and  pull  themselves  down  against 
the  plant  to  which  the  stem  is  attached.  And  in  still 


INFUSORIA.  135 

others,  the  Vorticellce,  there  is  but  one  stem  with  a  sin- 
gle bell-shaped  body  on  the  end,  but  the  stem  contracts 
into  close  spirals  and  suddenly  draws  the  animal  down. 
When  the  danger  is  past,  the  stem  slowly  uncoils,  the 
branches  spread  themselves,  the  animals  expand,  and  all 
is  as  before.  Indeed,  the  variety  of  form  and  habit  in: 
the  Infusoria  is  almost  infinitely  great. 

The  general  opinion  is  that  "animalcules"  have  no 
color.  This  is  a  mistake.  The  majority  are  almost  col- 
orless, but  green,  crimson,  yellow,  indigo  blue  or  almost 
black  Infusoria  are  not  uncommon,  and  the  loricse,  as" 
stated,  often  become  brown. 

The  free-swimming  Infusoria  are  more  abundant  than 
the  attached  ones,  and  much  more  difficult  to  examine 
because  they  will  never  stand  still.  But  how  do  these 
creatures,  all  of  which  are  invisible  without  the  micro- 
scope— how  do  they  move  ?  For  this  purpose  they  have 
organs  of  two  kinds,  and  they  are  separated  into  two 
great  classes  according  as  they  possess  the  one  kind,  or 
the  other.  In  some  there  are  one  or  more  long,  color- 
less lashes  which  extend  from  the  front  of  the  body> 
beat  against  the  water,  and  so  row  the  animal  about  very 
rapidly.  Each  of  these  lashes  is  called  zflagellum  (ipln- 
T2\,  flagella).  In  others  there  are  on  the  body  short, 
very  fine  hairs,  which  are  continually  vibrating  so  rap- 
idly that  they  are  often  invisible  even  under  a  high- 
power  objective.  The  short  hairs  are  called  cilia,  and  it 
is  their  action  on  the  water  that  urges  the  animal  about 
even  more  quickly  than  the  flagella.  The  cilia  may  be 


136  MICROSCOPY  FOR  BEGINNERS. 

confined  to  a  circle  around  one  end,  or  they  may  be  on 
the  lower  surface  only,  or  the  whole  body  may  be  cov- 
ered with  them.  Infusoria  with  cilia  are  more  numer- 
ous than  Infusoria  with  flagella.  They  are,  however, 
not  the  only  ciliated  animals.  The  Eotifers  are  well 
supplied,  and  certain  small  aquatic  worms  have  the  en- 
tire body  ciliated. 

Although  the  Infusoria  are  so  abundant  that  scarcely 
a  drop  from  any  pond  or  ditch  can  be  examined  with- 
out exhibiting  some,  the  beginner  will,  I  fear,  have  trou- 
ble in  studying  them,  they  are  so  lively  and  so  small. 
The  stage  must  be  kept  in  continuous  motion  to  coun- 
teract the  motions  of  the  Infusorium  and  keep  it  in  the 
field,  so  it  can  be  seen  as  anything  more  than  a  whirling 
speck,  and  high-powers  are  needed  to  examine  it.  But 
the  beginner's  object  will  be  gained  if  he  learns  to  know 
an  Infusorium  when  he  sees  one,  and  if  he  learns  the 
names  of  some  of  the  largest  and  commonest.  Many 
can  be  seen  with  a  one-inch  objective,  but  to  ascertain 
whether  any  special  one  has  cilia  or  flagella  will  demand 
a  one-fifth  inch  or  higher  power  lens,  and  without  know- 
ing this  the  Infusorium  cannot  be  identified.  But  "it 
is  only  the  first  step  that  costs."  Any  work  or  study  is 
always  hardest  at  the  beginning.  When  the  student  has 
identified  one  Infusorium  he  will  have  little  trouble  with 
what  comes  after.  The  attached  forms  will  not  be  very 
difficult  even  at  the  first,  if  a  sufficient  magnifying  pow- 
er is  used,  for  since  they  are  fastened  by  stem  or  lorica 
to  another  object,  they  can  be  examined  at  leisure. 


INFUSORIA.  137 

None  of  these  creatures  can  be  preserved  as  perma- 
nently mounted  objects.  Many  chemical  solutions  and 
mixtures  have  been  recommended  for  killing  and  keep- 
ing them,  but  none  are  satisfactory,  the  soft  bodies  go- 
ing to  pieces  and  melting  away  almost  as  soon  as  after  a 
natural  death.  If  the  beginner  is  very  much  annoyed  by 
the  incessant  movements  of  the  free-swimming  kinds, 
and  he  desires  to  see  how  they  look  when  quiet  for  a 
moment,  the  following  solution  will  help.  It  answers 
the  purpose  well  in  some  cases,  while  in  others  it  is 
worthless.  It  always  kills,  but  does  not  always  preserve 
after  death.  It  is  used  by  allowing  a  small  drop  to  run. 
under  the  cover-glass  and  to  mingle  with  the  drop  of 
water  containing  the  Infusoria.  Any  druggist  can  make 
it,  but  caution  him  to  use  not  more  than  half  a  drachm 
(half  a  teaspoonf  ul)  of  water,  or  you  will  be  terrified  by 
his  bill.  If  this  small  quantity  is  made  it  is  not  expen- 
sive. 

To  the  half  drachm  of  water  add  as  much  iodide  of 
potassium  as  it  can  be  made  to  dissolve,  and  to  this  so- 
lution add  as  much  iodine  as  the  .solution  can  be  forced 
to  dissolve.  This  ends  the  druggist's  part.  It  only  re- 
mains for  you  to  add  enough  of  the  mixture  to  clean 
water  to  make  the  color  a  rather  deep  amber.  The 
proper  strength  can  be  learned  by  experiment.  If  it 
kills,  and  then  destroys  too  quickly,  add  more  water ;  if 
it  does  not  kill  quickly  enough,  drop  in  a  little  more  of 
the  iodine  mixture. 

A  weak  solution  in  water  of  the^r-chloride  of  iron 


138  MICROSCOPY  FOR  BEGINNERS. 

Las  also  been  recommended  for  this  purpose,  but  its  ac- 
tion is  similar  to  that  of  the  iodine  solution,  and  not 
more  satisfactory. 

The  following  Key  refers  to  only  a  few  of  the  com- 
monest Infusoria  in  fresh  water  and  vegetable  infusions. 
To  include  a  tithe  of  those  most  frequently  seen  in  such 
places  is  an  impossibility.  When  the  beginner  learns 
that  there  are  fifty  known  species  of  Yorticella  alone, 
and  about  thirty  of  Monad,  he  will  see  that  it  is  possi- 
ble to  refer  in  the  most  superficial  way  to  only  a  very 
few  of  these  abundant  and  attractive  creatures. 

Key  to  some  Genera  of  Infusoria. 

1.  Free-swimming  (f). 

2.  Not  free-swimming;  singly  or  in  clusters  on  a  stem  (a). 

3.  Not  free  -  swimming ;  in  a  transparent  or  granular 

lorica  (&). 

a.  Stem  much  branched,  neither  it  nor  the  animals 
contractile.  Dendromonas,  1. 

a.  Stem  much  branched,  both  it  and  the  animals  con- 
tractile. Carchesiitm,  2. 

a.  Stern  much  branched,  only  the  animals  contrac- 
tile. Epistylis,  3. 

a.  Stem  not  branched,  contracting  into  spirals.     Vor- 

ticella,  4. 

b.  Loricse  vase-shaped,  transparent  (c). 
5.  Loricee  soft,  granular,  brownish  (e). 

c.  Attached  to  each  other  to  form  colonies.    Dino- 

bryon,  5. 


INFUSORIA.  139 

c.  Not  attached  to  each  other  (d). 

d.  Lorica  without  a  stem,  adherent  by  the  narrow 

base.      Vagiiucola,  6. 

d.  Lorica  without  a  stem,  adherent  by  the  broad  side. 
Platycola,  7. 

d.  Lorica  with  a  short  stem.     Cothurnia,  8. 

e.  Extended  animal  trumpet-shaped.     Stentor,  9. 
f.  With  one  or  more  flagella  at  the  front  (g). 

f.  Without  flagella,  but  with  cilia  (A). 

g.  Body  very  changeable  in  shape,  colorless.     Asia- 

sia,  10. 
g.  Body  very  changeable  in   shape,  green   or  red. 

Euglena,  11. 
g.  Body  not  changeable  in  shape,  colorless,  notched 

in  front.     Chilomonas,  12. 
g.  Body  not  changeable  in  shape,  green,  with  a  short, 

stiff,  colorless  tail.     P hocus,  13. 
g.  Body  not  changeable  in  shape,  green,  united  in  a 

revolving  colony.     Uvella,  14. 
h.  Cilia  on  the  entire  surface  (i). 
h.  Cilia  confined  to  the  lower  or  flat  surface  (&). 
i.  Neck  long,  very  elastic  and  extensile.     Trachelo- 

cerca,  15. 
i.  Neck  long,  flattened,  not  extensile.     Ampkileptus, 

16. 

i.  Body  brownish,  slipper-shaped.    Paramcecium,  17. 
i.  Body  green,  red,  blue  or  almost  black ;  ovoid  or 

trumpet-shaped ;  cilia  largest  on  the  front.    Sten- 

tor,  9. 


140  MICROSCOPY  FOR  BEGINNERS. 

k.  Cilia  large,  few,  scattered  (I). 

k.  Cilia  fine,  numerous  (m). 

1.  Body  more  or  less  circular  in  outline.  Euplotes, 
IS. 

I.  Body  more  or  less  oblong  in  outline.  Stylonychia, 
19. 

m.  Month  followed  by  a  conical  tube  of  rods.  Chi- 
lodon,  20. 

m.  Mouth  followed  by  a  brown,  sickle-shaped  mem- 
brane. Loxodes,  21. 

1.  DENDKOMONAS  (Fig.  106). 

The  stem  is  many  times  divided  into  numerous 
branches,  and  the  branches  themselves  are  also  much 
divided,  with  one  small  Infusorium  at  the  end  of  each. 
The  whole  has  a  beautiful  but  colorless 
tree-like  appearance,  the  stem  being  often 
found  attached  to  Ceratophyllum.  The 
animals  have  each  two  flagella,  but  they 
are  visible  only  to  a  high-power  objective. 
There  is  no  special  mouth.  A  particle  of 
food  dashed  down  by  the  flagella  against 
any  part  of  the  body  sinks  into  its  soft 
side  and  is  thus  swallowed  without  a  throat.  The 
whole  colony  is  often  more  branched  than  is  shown  in 
the  figure.  It  can  be  recognized  with  a  good  one-inch 
objective. 

2.  CARCHESIUM  (Fig.  107). 
The  stem,  attached  to  plants  or  other  submerged 


INFUSORIA.  141 

objects,  is  divided  at  the  summit  into  many  branches, 
with  one  Infusorium  at  the  end  of  each,  and  many  oth- 
ers scattered  along  them  with  shorter  branches  of  their 
own.  Through  the  main  stem  and  through  all  the 
branches  there  extends  a  cord-like  muscular  thread  that 
suddenly  contracts  when  the  animals  are  frightened  or 
disturbed,  and  pulls  the  whole  colony  down  towards  the 
point  of  attachment  to  the  plant.  But  the  branches 
may  contract  one  at  a 
time  and  draw  their  bur- 
den of  Infusorial  fruit 
down  to  the  main  stem 
without  disturbing  any 
other  portion  of  the  col- 
ony, or  all  the  branches 
may  contract  at  once. 

Therefore,  while  the  ani-  F,g  toT._Carch6gium. 

mals  on  the  branches  are 

connected  together,  they  are  still  somewhat  independ- 
ent. The  front  border  of  each  body  is  surrounded  by 
a  circle  of  cilia  visible  under  a  high  power.  They 
are  the  only  cilia  on  the  body.  When  the  animal  is 
contracted  they  are  folded  together,  each  body  then 
resembling  a  little  ball.  They  vibrate  rapidly,  produc- 
ing circular  currents  that  bring  to  the  mouth  any  food- 
particles  that  may  be  in  the  vicinity.  The  entire  col- 
ony is  colorless,  and  may  include  as  many  as  a  hundred 
Infusoria  on  the  branches.  It  can  be  seen  by  a  low- 
power  objective.  The  independent  contraction  of  the 


142  MICROSCOPY  FOR  BEGINNERS. 

branches  and  the  stem  will  distinguish  it  from  all  other 
tree-like  Infusoria. 

3.  EPISTYLIS  (Fig.  103). 

As  in  the  two  preceding,  the  stem  of  Epistylis  is 
also  often  much  branched.  The  Infusoria  at  the  ends 
of  the  branches  can  alone  contract,  which  they  often  do 
with  a  jerk,  settling  back  as  if  they  meant  to  impale 
themselves,  or  dropping  and  nodding  like  flowers  fad- 
ing on  their  stems.  The  bodies  of  the  expanded  ani- 
mals are  somewhat  bell-shaped,  their  widest  part  being 
the  free  end  which  closes  when  the  body  contracts. 
The  front  border  is  encircled  by  a  row  of 
cilia,  to  be  properly  discerned  only  by  a 
high-power  objective.  The  one-inch  glass, 
however,  will  show  the  rapid  currents  pro- 
duced, because  all  small  particles  in  their 
neighborhood  are  caught  up  and  dashed 
around  in  the  mimic  whirlpools.  The  ani- 
mals select  from  these  streams  anything 
they  may  want  and  let  the  rest  sweep  by. 
They  have  a  distinct  mouth  near  the  centre 
of  the  front  part.  The  entire  colony  is  usually  colorless. 
It  is  often  attached  to  Ceratophyllum. 

4.  VORTICELLA  (Fig.  109). 

The  unbranched  stem  of  Vorticella  contains  a  zigzag 
muscular  thread  like  a  thin  cord,  which  contracts  into 
close  coils  very  suddenly,  and  draws  the  Infusorium 


INFUSORIA.  143 

down  with  it.  The  Yorticellse  are  very  common,  scarce- 
ly a  leaflet  of  any  aquatic  plant  is  without  them.  They 
are  usually  colorless,  although  green  ones  do  occur. 
The  body  is  bell-shaped,  the  narrow  part  of  the  bell  be- 
ing fastened  to  the  top  of  the  stem.  The  front  border 
is  surrounded  by  a  circle  of  fine  cilia  which  need  a  high 
power  to  show  them.  They  produce  currents  in  the 
water  similar  to  those  of  Epistylis,  and  for  the  same 
food-collecting  purposes. 

The  contractions  are  surprising  in  their  suddenness. 
While  the  observer  is  quietly  gazing  at  the  graceful 
creature  whirling  its  cilia  and  making  tre- 
mendous whirlpools  on  a  small  scale,  it  dis- 
appears like  a  flash,  and  the  student  feels 
like  looking  for  it  on  the  table.     But  pres- 
ently it  slowly  begins  to  rise  from  the  plant 
against  which   it  was   crouching,  and  the 
coiled    stem   lengthens   as    it    straightens. 
Yery  often  it  hardly  extends  before  it  again  leaps  out 
of  sight,  or  close  to  the  object  supporting  the  stem; 
"When  the  stem  throws  itself  into  spirals,  the  body  of 
the  animal  folds  together  into  a  ball. 

This  will  probably  be  one  of  the  first  Infusoria  to  at- 
tract the  beginner's  attention,  and  he  will  think  it  a 
wonderful  thing,  as  it  is.  The  figure  shows  some  ex- 
tended and  some  contracted.  They  are  often  found  in 
clusters,  sometimes  of  a  hundred  or  more,  all  bobbing 
and  swaying  in  a  very  curious  way,  for  when  one  con- 
tracts it  usually  sets  them  all  off. 


144  MICROSCOPY  FOR  BEGINNERS. 

5.  DINOBRYON  (Fig.  110). 

In  the  early  spring,  as  early  as  March,  among  the 
Algae  then  found  so  abundantly  in  the  shallow  pools, 
colonies  of  very  small,  vase-shaped  loricse  are  often  ob- 
tained. They  are  sometimes  attached  to  a  plant  or  fila- 
ment of  alga,  or  as  often  they  float  freely  through  the 
water,  being  fastened  to  the  plant  by  a  very  slight  hold. 
The  loricae  are  transparent  and  colorless,  and  may  be 
overlooked,  but  the  Infusorium  within  each 
one  is  rather  conspicuous  to  even  a  low-pow- 
er objective,  for  it  has  a  narrow  green  band 
on  each  side  of  the  body,  and  often  a  minute 
red  eye-like  spot  in  the  centre  of  the  front 
border.  The  loricse  are  united  together  by 
one  or  two  being  attached  to  the  front  edge 
of  the  one  behind  them,  until  branching  colonies  of 
some  size  are  formed.  The  front  border  of  each  en- 
closed Infusorium  bears  two  flagella,  one  long  and  one 
short,  but  they  are  seen  with  difficulty  even  with  a  mod- 
erately high-power  objective.  The  lashing  of  all  the 
flagella  in  a  large  colony  urges  it  quite  rapidly  through 
the  water.  According  to  my  experience  Dinobryon  is 
seldom  found  in  the  summer. 

6.  VAGINICOLA  (Fig.  111). 

The  lorica  is  colorless,  transparent,  and  about  three 
times  as  long  as  broad.  In  form  it  is  long,  vase-shaped, 
or  nearly  cylindrical,  the  base,  or  the  part  fastened  to 
the  plant  or  other  object,  being  usually  rounded.  The 


INFUSORIA.  145 

animal,  when  it  projects,  extends  for  a  considerable  dis- 
tance beyond  the  opening  at  the  front  of  the  lorica. 
When  frightened,  or  disturbed  in  any  way,  it  quickly 
closes  up  its  broader  front  part,  and  retreats  as  far  into 
the  lorica  as  possible.  When  recovered  from  its  fright 
it  slowly  ascends  to  the  opening,  expands  it- 
self and  resumes  its  fishing  operations.  It  is 
fastened  to  the  extreme  end  of  the  lorica  by 
the  tip  of  the  body ;  from  the  sides  it  is  en- 
tirely free.  On  its  front  border  it  has  a 
wreath  of  fine  cilia  in  continuous  motion  Fls-ni— Va- 

ginicola. 

when  the  animal  is  extended.  The  body  is 
soft  and  flexible,  and  is  sometimes  of  a  pale  greenish 
tint,  but  the  lorica,  I  think,  seldom  changes  color  with 
age.  It  is  not  uncommon  to  find  two  bodies  in  one 
sheath,  where  they  seem  to  live  together  in  peace  and 
harmony.  This  may  be  an  advantage  to  both,  for  two 
wreaths  of  cilia  can,  of  course,  produce  stronger  cur- 
rents, and  so  bring  more  food  to  the  mouths  of  the 
always  hungry  creatures.  Vayinwola  is  quite  common 
on  Lemna  and  Myriophyllum. 

7.  PLATYCOLA  (Fig.  112). 

The  lorica  is  flattened,  and  is  in  outline  almost  circu- 
lar. It  is  always  adherent  to  some  submerged  object  by 
the  broad  flat  side,  the  opposite  or  upper  surface  being 
convex.  The  opening,  through  which  the  animal  ex- 
tends itself  as  in  Yaginicola,  is  at  one  end,  and  is  often 
prolonged  into  a  short  neck.  The  figure  shows  a  side 


146  MICROSCOPY  FOR  BEGINNERS. 

view  with  tlie  animal  extended.  When  young  the  lor- 
ica  is  colorless,  but  it  very  soon  changes  to  a  deep 
brown,  often  becoming  so  opaque  that 
the  body  of  the  Infusorium  cannot  be 
seen  through  its  walls.  The  body  is 

Fig.  112. —Platycola.  6  .      J 

usually  colorless ;  it  is  attached  by  its 
tip  to  the  side  opposite  the  mouth  of  the  lorica.  When 
frightened  it  darts  back  into  the  shell  as  Vaginicola 
does.  Two  animals  are  not  seldom  found  in  one  lorica. 
It  is  not  uncommon  on  Ceratophyllum  and  other  aquatic 
plants. 

8.  COTHTJRNIA  (Fig.  113). 

The  beginner  may  mistake  this  for  a  small  Vaginicola, 
as  the  loricae  somewhat  resemble  each  other  in  shape ; 
but  Cothurnia  can  always  be  known  by  the  little  stem 
or  foot-stalk  that  lifts  it  a  short  distance  from  the  plant 
to  which  it  is  attached.  This  foot-stalk  in  some  species 
is  very  short,  and  must  be  especially  looked 

ffor.     The  lorica  is  vase -shaped,  often  with 
the  sides  variously  curved.     It  changes  to  a 
brown  color  as  it  grows  old.     The  body  of 
Fig.  us.     the  enclosed  Infusorium-is  not  colored.    In  its 
actions  it  resembles  Yaginicola  and  Platycola, 
being  similarly  attached  to  the  posterior  end  of  the  lor- 
ica, and  having  a  similar  circle  or  wreath  of  cilia  around 
the  front  border.     Two  animals  are  sometimes  found  in 
one  lorica. 

9.  STENTOR  (Figs.  114,  115,  116). 
The  Stentors  vary  a  good  deal  in  shape  in  the  same 


INFUSORIA.  147 

species,  the  bodies  of  all  being  somewhat  changeable  in 
form.  The  largest  ones  are  trumpet-shaped,  and  are 
usually  attached  to  some  object  by  the  narrow  .end  of 
the  body.  They  also  commonly  form  a  soft,  brownish, 
granular  sheath  or  lorica,  to  the  bottom  of  which  they 
retreat  when  disturbed,  folding  together  the  wide  trum- 
pet-shaped front  border.  The  entire  surface  of  the  body 
in  all  the  species  is  ciliated,  but  the  cilia  are  very  small 
and  fine.  Around  the  edge  of  the  front  border  is  a  cir- 
cle of  longer  and  larger  vibratile  hairs,  visible  with  a 
moderately  low  power.  The  Stentors  are  all  common. 
The  following  Key  may  help  the  beginner  to  recognize 
some  of  those  most  frequently  seen. 

Key  to  some  species  of  Stentor. 

1.  Attached,  and  usually  forming  a  short,  soft  sheath  (a). 

2.  Free-swimming,  more  or  less  ovoid ;  green,  red,  blue 

or  almost  black  (J). 

a.  Body  large,  trumpet-shaped,  greenish  • 
often  without  a  visible  sheath,  and 
when  one  is  formed  it  is  sometimes 
soon  abandoned,  the  Stentor  swim- 
ming about  freely.  The  body  is 
slightly  changeable  in  shape.  Sev- 
eral Stentors  of  this  species  are  often 
found  close  together,  having  formed 
a  very  soft  sheath  divided  into  irreg- 
ular compartments,  one  for  each  Infusorium.  S. 
polymorphus.  Fig.  114:. 


148  MICROSCOPY  FOR  BEGINNERS. 

a.  Body  long,  and  narrowly  trumpet-shaped,  the  front 

divided  into  two  lobes,  one  of  which  is  almost  at 
right  angles  to  the  other.     The  body  has  many 
long,  fine  hairs  projecting  from  it,  and 
visible  under  a  high-power  (^  inch)  ob- 
jective.    The  sheath  is  always  present. 
It   is   narrow,   cylindrical,   brown,  and 
about  one-half  as  long  as  the  extended 
body.     This  Stentor  is  never  free-swim- 
.—  ming>  and  ig  never  found  in  company 
ntor     wjtjj  others  of  the  same  species.     It  is 

Barretti. 

not  uncommon  on  Ceratophyllum.     S. 
Barretti,  Fig.  115. 

J.  Body  green  or  red,  the  red  color  often  being  lim- 
ited to  the  part  just  beneath  the  wide  front  bor- 
der where  the  circle  of  large  cilia  is.    Sometimes 
the  red  color  is  diffused  over  the  whole  body,  but 
usually  the  green  matter  so  obscures  it  that  it  is 
invisible.     This    species   is   often   ex-         ^ 
tremely   abundant  at    the   bottom   of        Jfjp' 
shallow  ponds  in  early  spring.      The        r 
green  color  then  always  entirely  con-      stentor 
ceals  the  red.     S.  igneus,  Fig.  116.  igneu8' 

b.  Body  large,  indigo  blue.     This  in  shape  resembles 

Fig.  114  when  extended ;  when  contracted  it  is 
not  unlike  Fig.  116.  Yery  common  in  some  lo- 
calities. S.  ccerideus, 

b.  Body  dark  brown,  almost  black.     This  also  resem- 
bles Fig.  116.     Common.     S.  niger. 


INFUSORIA.  149 

10.  ASTASIA  (Fig.  117). 

Body  long  and  narrow,  very  soft,  and  changeable  in 
shape,  altering  its  form  as  it  glides  over  the  slide,  which 
it  does  quite  rapidly.  It  has  one  long  straight  flagellum 
at  the  front.  It  is  quite  common. 


Fig.  117.— Astteia.  Fig.  118.— Euglena. 

11.   EUGLENA  (Fig.  118). 

Body  long  and  rather  narrow,  being  widest  in  the 
middle  and  tapering  to  both  ends.  It  is  very  change- 
able in  form,  and  bright  green  or  red  in  color.  The 
front  end  is  seen  witli  a  high  power  to  be  notched  as 
if  the  Infusorium  had  two  lips,  the  long,  vibrating,  and 
colorless  flagellum  appearing  to  issue  from  the  notch. 
There  is  sometimes  a  small  red  spot  near  the  front  end, 
supposed  to  be  an  imperfect  eye.  It  is  often  absent  in 
an  old  Euglena.  At  the  posterior  end  is  a  short,  point- 
ed, stiff,  and  sometimes  curved  tail,  which  is  usually  col- 
orless. The  Infusorium  is  common,  occasionally  occur- 
ring in  such  immense  numbers  that  it  tinges  the  water 
green.  There  is  another  species,  or  another  variety  of 
this  species,  whose  body  is  bright  crimson.  It  also  is 
so  abundant  at  times  that  it  colors  the  water  blood  red. 

12.  CHILOMONAS  (Fig.  119). 

This  colorless  little  creature  is  very  common  in  vege- 
table infusions.  It  may  be  recognized  by  the  notch  at 
the  widest  or  front  end,  and  the  curve  of  the  back 


150  MICROSCOPY  FOR  BEGINNERS. 

which  makes  it  look  almost  hunch -backed.  Under  a 
high  power  it  shows  two  flagella,  one  of  them  throwing 
itself  into  a  coil  or  loop  when  the  Infusorium  settles 
down  to  rest,  which,  by -the -way,  it  quite  frequently 
does.  The  body  is  filled  with  small  colorless  disks 
which  the  iodine  solution  turns  blue,  showing  that  they 
are  starchy. 


Fig.  119.— Chil<S-  Fig.  120.— Phicns  Fig.  121.—  Phdcns 

monas.  pleuron£ctes.  longicuudns. 

13.  PHACUS  (Figs.  120,  121). 

The  body  of  Phdcus  is  flattened,  thin,  and  rather  like 
a  small  leaf.  It  is  widest  in  front,  usually  rounded,  and 
tapering  from  the  centre  to  the  short,  pointed,  colorless 
tail-like  prolongation ;  at  the  broad  end  it  has  one  long 
flagellum,  often  difficult  to  see.  There  are  several  spe- 
cies in  our  ponds,  all  of  which  are  green. 

1.  Body  not  twisted  at  the  rear,  tail  short,  curved.    Ph. 

pleuronectes,  Fig.  120. 

2.  Body  twisted  or  not  at  the  rear,  tail  long,  straight. 

Ph.  lonfficaudus,  Fig.  121. 

14.  UVELLA  (Fig.  122). 

The  little  animals  forming  these  rapidly  swimming 
and  revolving  colonies  are  united  by  their  narrow  ends 
into  almost  spherical  microscopic  masses,  varying  in 


INFUSORIA.  151 

number  from  two  or  three  up  to  forty  or  fifty  or  more. 
Each  Infusorium  has  a  narrow,  yellowish  -  green  band 
down  each  side  of  the  somewhat  egg-shaped  body,  and 
two  long,  fine  flagella  at  the  broader  front  end.  The 
colonies  are  common  in  early  spring  in  shallow  pools 
with  Algae. 


¥15. 122.— Uvella.  Fig.  123.—  Trachelocerca. 

15.  TRACHELOCERCA  (Fig.  123). 

This  will  probably  be  a  greater  surprise  to  the  begin- 
ner the  first  time  he  sees  it  than  any  other  common  In- 
fusorium, on  account  of  the  remarkable  neck,  which  can 
be  stretched  out  to  five  or  six  times  the  length  of  the 
body,  and  drawn  back  until  it  almost  entirely  disap- 
pears. The  body,  without  the  neck,  is  somewhat  spin- 
dle-shaped, and  occasionally  ends  in  a  short,  tail-like  part. 
The  Infusorium  may  often  be  concealed  in  a  mass  of 
fragments  or  a  heap  of  dirt,  while  only  that  wonderful 
neck  is  visible,  stretching  and  bending  and  writhing  like 
a  colorless  snake,  as  it  searches  the  slide  for  food.  The 
end  of  the  neck  is  rather  pointed,  and  bears  the  mouth 
at  the  tip.  The  whole  Infusorium  is  covered  with  fine 
cilia.  It  is  quite  common. 

16.  AMPHILEPTUS  (Fig.  124). 
This  is  one  of  the  largest  of  the  Infusoria,  sometimes 


152  MICROSCOPY  FOR  BEGINNERS. 

measuring  -^  inch  in  length.    The  neck  is  not  extensile 
as  in  Trachelocerca,  although  it  is  the  longest  part  of  the 
whole  animal.    The  body, 
without  the  neck,  is  some- 
what spindle-shaped,  taper- 
rig.  124.-Amphil6ptti9. 

ing  more  rapidly  towards 

the  rear  than  towards  the  front.  The  latter  or  neck- 
like  part  is  flexible,  and  is  turned  and  twisted  about  in 
a  way  that  often  suggests  the  movements  of  an  ele- 
phant's trunk.  The  whole  body  is  covered  with  fine 

cilia. 

17.  PAKAM^CTOM  (Fig.  125). 

This  is  often  called  the  "  slipper  animalcule  "  from  its 
shape.  It  is  frequently  found  in  the  ponds,  but  is  espe- 
cially abundant  in  vegetable  infusions.  The  hollow 
place  resembling  the  opening  in  the  slipper  for  the  foot, 
is  the  part  leading  to  the  mouth  near  the  centre  of  the 
lower  surface.  The  whole  body  is  cov- 
ered with  fine  cilia,  and  sometimes  a  clus- 
ter of  longer,  coarser  cilia  is  noticeable  on  rig.  125.— Para- 
the  posterior  tip  of  the  body.  In  the 
writer's  locality  this  cluster  of  cilia  is  present  on  all  the 
specimens ;  I  have  never  seen  a  Paramcecium  without 
it.  This  Infusorium  increases  rapidly  by  dividing  into 
two  parts  across  the  middle.  Its  movements  are  rapid. 

18.  EUPL6TES  (Fig.  126). 

This  is  one  of  the  walking  Infusoria,  the  cilia  on  the 
flat  lower  surface  being  very  large  and  strong.     The 


INFUSORIA.  153 

animal  uses  them  for  swimming,  or  it  walks  about  the 
slide  or  climbs  among  aquatic  plants  by  resting  part  of 
its  weight  on  their  tips  as  if  they  were  legs.  When  the 
creature  happens  to  be  turned  on  its  back,  these  large 
cilia  can  be  seen  pattering  irregularly  against  the  cover- 
glass.  They  vary  in  number  from  ten  to 
twelve.  The  front  border  has  a  row  of 
finer  but  still  large  cilia  extending  down  the 
side  of  the  flat  surface  to  the  mouth  near  the 
centre  of  the  body.  Four  straight,  stiff  hairs 
project  from  the  posterior  margin,  two  of  P16tes- 
them  often  being  divided  into  fine  branches.  The  back 
of  the  Infusorium  has  no  cilia,  but  is  a  hard  surface,  al- 
most like  a  shell.  The  animal  is  very  active.  There 
are  several  species  common  among  Ceratophyllum  and 
Myriophyllum. 

19.  STTLONYCHIA  (Fig.  127). 

To  the  beginner  the  members  of  this  genus  will  quite 
closely  resemble  Euplotes,  as  all  the  cilia  are  confined 
to  the  frontal  border,  the  part  about  the 
mouth,  and  irregularly  distributed  over  one 
side  of  the  flat  lower  surface  as  walking  or- 
gans. It  can  easily  be  distinguished  from 
Euplotes  by  its  shape,  being  much  more  ob- 
long.  Sometimes  it  is  quite  long  and  nar- 

i  -i      -n       i    i         •         i  i 

row,  while  Luplotes  is  always  more  or  less 
circular.  It  has  no  cilia  on  the  back,  which  is  usually 
hard  and  shell-like.  The  species  are  several,  being  espe- 
cially common  in  vegetable  infusions. 


154  MICROSCOPY  FOR  BEGINNERS. 

20.  CnfLODON  (Fig.  128). 

The  body  is  oval  and  flattened,  the  lower  or  flat  sur- 
face alone  being  ciliated.  The  front  border  is  convex, 
and  rather  sharply  pointed  at  one  comer,  and  the  side 
of  the  body  extending  from  this  corner  to  the  rounded 
posterior  margin  is  nearly  straight,  while  the  opposite 
side  is  convex.  The  back  is  smooth  and  naked. 
From  the  pointed  corner  a  curved  line  of  cilia 
extends  back  over  the  flat  surface  to  the  mouth, 
which  opens  into  a  cone-shaped  bundle  of  fine 
rods  visible  under  a  high  power.  The  ends  of 
these  rods  can  be  seen  with  a  moderately  low  power,  en- 
circling the  mouth  like  beads.  The  Infusorium  lives 
upon  smaller  Infusoria  and  diatoms,  which  it  appears  to 
seize  with  this  peculiar  throat,  the  rods  separating  as  the 
food  is  slowly  swallowed.  Chttodoti  is  common  in  still 
waters. 

21.  LOXODES  (Fig.  129). 

The  body  is  quite  long  and  narrow,  the  frontal  border 
being  convex,  with  one  corner  rather  pointed ;  but  on  one 
side,  just  below  the  pointed  corner,  is  a  concave  space  con- 
taining a  brown,  sickle-shaped  body  lining  the 
hollow  which  is  part  of  the  Infusorium's  throat. 
The  upper  portion,  or  blade  of  the  sickle,  seems 
only  to  stiffen  that  part  of  the  cavity,  the  true 
mouth  being  at  the  beginning  of  the  short  handle  rig"  129. 
of  the  sickle.  The  cilia  are  fine,  and  are  on  the  low-  Lo:s6de8' 
er  flat  surface  only.  The  body  is  flexible,  often  bending  on 
itself.  The  Infusorium  is  quite  common  in  some  localities. 


HYDRAS.  155 


CHAPTER  VI. 

HYDKA8. 

WHEN  Hercules  was  going  about  doing  those  wonder- 
ful things  of  which  we  have  all  heard,  it  was  suggested 
that  he  should  turn  his  attention  in  the  direction  of 
Lake  Lerna,  near  Argos,  where  a  monster  with  a  hun- 
dred heads  was  making  itself  unpleasantly  active.  He 
visited  the  place  and  interviewed  the  creature,  but  when 
he  had  cut  off  one  of  the  heads,  he  must  have  been  sur- 
prised to  see  two  new  ones  sprout  out  of  the  bleeding 
surface.  It  was  discouraging,  but  the  hero  began  to 
have  the  best  of  the  contest  when  he  began  to  burn  the 
fresh  cuts  with  a  hot  iron.  The  monster  was  the  Hy- 
dra of  mythology.  Science  has  preserved  its  memory 
by  giving  the  name  to  a  common  and  curious  creature 
inhabiting  all  our  ponds  and  ditches.  The  fresh-water 
Hydra  (there  are  no  salt-water  Hydras)  has  a  soft  and 
elastic  body  attached  by  the  tip  of  one  end  to  an  aquat- 
ic plant  or  other  submerged  object,  and  eight  or  ten 
long  fine  arms  arranged  around  a  mouth  at  the  op- 
posite end. 

There  are  two  species,  the  green  (II.  mridis)  and  the 

brown  (H.fusca),  both  being  very  common.    The  whole 

animal  is  elastic,  and  when  extended  may  be  an  inch 

long  and  easily  visible  to  the  naked  eye ;  when  con- 

8 


156 


MICROSCOPY  FOR  BEGINNERS. 


tracted  it  resembles  a  minute  globule  of  green  or  brown 
jelly,  with  the  shortened  arms  at  the  summit  like  very 
small  drops  or  projections.  It  is  very  active  so  far  as 
the  arms  are  concerned,  for  the  body  is  always  adherent 
to  some  submerged  object.  The  arms  or  tentacles  are 
usually  stretched  out  to  their  fullest  extent,  then  often 
exceeding  the  body  in  length,  waving  and  twisting  about 
in  search  of  prey.  The  figure  (Fig.  130)  shows  several 


Pig.  130.— Hydras  adherent  to  Lerana  rootlets. 

Hydras  nearly  the  natural  size  adherent  to  Lemna  root- 
lets. The  body  is  like  a  narrow  bag,  the  hollow  part 
of  the  little  sack  being  the  stomach,  and  communicating 
directly  with  the  external  water,  in  which  the  Hydra 
lives,  by  means  of  the  mouth,  around  which  are  arranged 
the  arms  or  tentacles.  These  tentacles  are  themselves 
hollow,  and  communicate  with  the  hollow  of  the  stomach. 


HYDRAS.  157 

The  food  consists  of  small  worms,  water-fleas,  or  other 
Entomostraca  (Chapter  X.),  or  even  little  pieces  of  raw 
beef,  if  the  observer  chooses  to  feed  them.  They  seize 
the  victim  as  it  is  swimming  past,  by  twining  a  tentacle 
around  it  and  drawing  the  struggling  creature  down  to 
the  mouth,  through  which  it  is  thrust  into  the  stomach. 
The  act  of  seizure  takes  place  so  rapidly  that  the  eye 
can  seldom  follow  it.  The  observer  can  usually  only 
know  that  the  prey  is  caught  and  is  slowly  approach- 
ing the  mouth.  Often  when  the  captured  object  is  too 
large  or  strong  for  one  arm  to  hold,  several  tentacles 
bend  over  and  twine  around  it.  A  creature  once  caught 
rarely  escapes.  When  a  quantity  of  aquatic  plants  is 
brought  home,  the  Hydras  soon  make  their  way  to  the 
lightest  side  of  the  -aquarium  or  bottle  and  attach  them- 
selves to  the  glass.  At  such  times  I  have  often  amused 
myself,  and  doubtless  pleased  the  Hydras,  by  feeding 
them  with  small  larvse  or  aquatic  worms.  Take  with 
the  forceps  a  small  aquatic  worm  by  one  end,  and  pre- 
sent the  wriggling  thing  to  a  Hydra's  arm.  No  second 
invitation  is  needed.  The  worm  is  embraced  as  quick 
as  a  flash,  and,  if  too  long  to  be  swallowed  all  at  once, 
part  of  it  will  hang  out  of  the  mouth  until  the  other 
end  is  partially  digested,  but  the  tentacles  will  not  cease 
to  fish  for  more.  It  is  said  that  if  the  Hydra  and  the 
worm  are  placed  in  a  very  deep  cell  under  the  micro- 
scope, the  performance  can  be  watched  through  a  low- 
power  objective.  I  have  never  succeeded  in  doing  this, 
but  there  is  no  trouble  in  feeding  them  in  an  aquarium. 


158         MICROSCOPY  FOR  BEGINNERS. 

They  never  eat  any  but  animal  food,  and  they  are  al- 
ways hungry. 

The  body  and  tentacles  of  Hydra  mridis  are  rough- 
ened by  little  elevations  or  warty  prominences.     The 
brown  species  (II.  fused)  is  not  so  much  roughened. 
These  warts  contain  what  are  called  the  stings.     These 
are  smajl  oval  or  vase-shaped  hollow  bodies,  with  a  fine 
thread  coiled  in  the  interior,  and  four  minute  spines 
near  the  summit.     When  the  Hydra  is  irri- 
tated by  the  pressure  of  the  cover-glass  these 
stings  are  thrown  out  violently,  and  the  long 
stiff  thread  can  be  well  seen.     When  in  the 
animal's  body  they  cannot  be  easily  examined. 
One  is  shown  much  magnified  in  Fig.  130<z. 
Fig.  isoo.      They  are  often  found  on  the  slide  when  no 

Hydra  sting.  . 

Hydra  is  to  be  seen,  and  they  are  sometimes 
noticeable  sticking  in  the  body  of  some  worm  or  larva 
that  has  escaped  a  fatal  embrace.  I  have  more  than 
once  found  a  Chironomus  larva  (Chapter  VII.)  in  a 
dying  condition  and  ornamented  by  a  spiral  band  of 
these  stings  in  its  skin,  it  having  evidently  had  a  tussle 
with  a  Hydra  and  escaped. 

The  Hydra  increases  in  numbers  rapidly  by  a  process 
of  budding.  A  little  protuberance  appears  on  one  side 
of  the  body,  enlarging  and  growing,  and  finally,  while 
still  attached  to  the  parent,  developing  tentacles,  then 
resembling  the  mature  animal  in  everything  except  size. 
And  it  is  not  unusual  to  see  one  or  more  still  younger 
Hydras  sprouting  from  these  before  they  are  free  from 


HYDRAS.  159 

the  parent,  so  that  the  old  Hydra  is  often  a  grandmoth^ 
er  before  she  is  a  mother.  The  young  one  is  hollow, 
and  communicates  with  the  hollow  of  the  parent.  It 
captures  food  like  the  parent,  and  it  is  said  to  be  no  un- 
common sight  to  see  the  old  and  the  young  both  seize 
the  same  worm.  In  such  cases  the  strongest  wins,  un- 
less the  worm  breaks  in  the  unfilial  struggle,  when  the 
parts  go  into  the  one  common  stomach.  Very  often 
two  young  Hydras  may  be  noticed  growing  from  the 
sides  of  a  single  older  one,  instances  of  which  are  shown 
in  Fig.  130.  The  budded  young  finally  separate  from 
the  parent,  then  leading  an  independent  life,  and  soon 
producing  young  Hydras  from  their  own  sides,  if  they 
have  not  already  done  so. 

The  creatures  are  very  hardy.  They  may  endure 
much  harsh  treatment,  and  seem  to  thrive  under  it. 
They  have  been  made  the  victims  of  many  apparently 
cruel  experiments,  but  they  are  probably  not  very  sen- 
sitive to  a  feeling  of  pain.  The  sensation  of  hunger, 
and  a  touch  delicate  enough  to  know  when  a  desirable 
morsel  or  an  obnoxious  object  comes  in  contact  with  the 
tentacles,  are  probably  the  extent  of  their  feelings. 
Trembley,  a  Dutch  naturalist  who  studied  the  Hydra 
as  long  ago  as  1739,  first  called  attention  to  the  harsh 
treatment  they  would  endure  and  live.  In  a  rather 
quaint,  old-fashioned  translation  it  is  said  that,  "If  one 
of  them  be  cut  in  two,  the  fore  part,  which  contains  the 
head  and  mouth  and  arms,  lengthens  itself,  creeps,  and 
eats  on  the  same  day.  The  tail  part  forms  a  head  and 


160  MICROSCOPY  FOR  BEGINNERS. 

mouth  at  the  wounded  end,  and  shoots  forth  arms  more 
or  less  speedily  as  the  heat  is  favorable.  If  the  polype 
be  cut  the  long  way  through  the  head,  stomach,  and 
body,  each  part  is  half  a  pipe,  with  half  a  head,  half  a 
mouth,  and  some  of  the  arms  at  one  of  its  ends.  The 
edges  of  these  half  pipes  gradually  round  themselves 
and  unite,  beginning  at  the  tail  end ;  the  half  mouth 
and  half  stomach  of  each  becomes  complete.  A  polype 
has  been  cut  lengthwise  at  seven  in  the  morning,  and  in 
eight  hours  afterwards  each  part  has  devoured  a  worm 
as  long  as  itself."  He  also  sliced  them  across,  and  found 
that  each  piece  developed  a  cluster  of  tentacles,  and  he 
finally  turned  them  inside  out,  and  in  a  few  days  the 
maltreated  creature  swallowed  food,  although  its  old  skin 
was  now  lining  its  stomach,  and  its  old  stomach  mem- 
brane had  now  become  its  skin. 

There  is  a  peculiar  parasitic  Infusorium  (Fig.  1305) 
often  seen  in  considerable  numbers  gliding  rapidly  over 
the  body  and  arms  of  the  Hydra,  especially  of  II.  vi- 
ridis.  They  do  not  seem  to  be  objectionable 
guests,  as  the  Hydra  never  appears  to  notice 
them.  It  is  said  that  they  infest  sick  or 
weakly  victims  only,  but  that  is  not  according 
to  the  writer's  experience,  if  the  condition  of 
the  Hydra  may  be  judged  by  appearance,  ac- 
tivity, and  appetite.  One  of  these  parasites 
is  shown  in  side  view  (Fig.  130&).  It  is  shaped  like 
a  short  dice-box,  with  a  circle  of  fine  cilia  at  each 
end,  but  none  on  the  rest  of  the  body.  It  glides  along 


HYDRAS.  161 

rapidly  on  the  ends  of  the  dice-box,  running  out  to  the 
tips  of  the  tentacles  and  skirting  fearlessly  around  the 
edges  of  the  mouth.  It  is  the  Trichodma  pediculus. 

The  Hydra  also  occasionally  has  another  form  of  In- 
fusorial parasite  running  over  its  skin.  This  is  some- 
what kidney-shaped,  and  has  cilia  only  on  one  surface  of 
the  body.  It  is  called  Kerona  polyporum.  It  does  not 
seem  so  common  as  Trichodina. 

If  the  observer  desires  to  preserve  the  Hydra  as  a  per- 
manently mounted  object  for  the  microscope,  he  may 
be  easily  gratified,  thanks  to  Mr.  A.  H.  Breckenfeld,* 
of  San  Francisco,  who  has  devised  an  admirable  method 
which  the  writer  has  tried  and  recommends.  Transfer 
the  Hydras  to  a  slip  in  a  large  drop  of  water,  where 
they  can  be  seen  if  the  slide  is  held  over  white  paper. 
When  their  tentacles  are  fully  extended,  "  quickly  move 
the  lamp  directly  under  the  drop,  with  the  top  of  the 
chimney  about  an  inch  beneath  the  slide,  and  hold  it  in 
that  position  for  about  three  to  five  seconds,  the  exact 
time  depending  principally  upon  the  intensity  of  the 
heat.  Then  quickly  remove  the  slide  and  place  it  upon 
a  slab  of  marble  or  metal.  When  cool,  pour  the  drop 
containing  the  zoophytes  into  the  prepared  cell  on  the 
slide  which  has  been  held  in  readiness ;  add  a  drop  or 
two  of  a  suitable  preservative  fluid,  arrange  the  little 
animals  if  necessary  by  means  of  a  needle  or  camel's- 
hair  brush  (using  very  great  care,  however,  as  the  ten- 

*  American  Monthly  Microscopical  Journal,  March,  1884,  p.  49. 


162  MICROSCOPY  FOR  BEGINNERS. 

tacles  will  be  destroyed  by  the  least  rough  handling), 
cover  with  thin  glass,  and  finish  as  in  the  case  of  any 
fluid  mount."  I  have  not  found  it  necessary  to  use  two 
slips  of  glass.  If  a  deep  shellac  cell  that  has  been  made 
for  some  time  and  is  perfectly  dry  and  hard  is  used,  the 
Hydras  may  be  placed  in  it  and  there  cooked  and  al- 
lowed to  remain.  "When  cold,  arrange  the  arms  if  neces- 
sary, add  a  drop  of  weak  glycerine  and  water,  and  ce- 
ment the  cover -glass  with  shellac.  The  Hydras  thus 
prepared  can  be  kept  indefinitely,  and  at  any  time 
shown  to  admiring  friends. 

Both  the  green  and  the  brown  species  are  abundant 
duiing  the  summer  among  Anacharis  and  Lemna. 


SOME  AQUATIC  WORMS,  ETC.  163 


CHAPTER  VII. 

SOME     AQUATIC     WORMS,     CH^ETONOTUS,    AND     CHIEONOMUS 
LAKVA. 

THE  collector  of  microscopical  objects  from  the  ponds 
and  slow  streams  is  doubtless  familiar  with  the  appear- 
ance of  the  bristle-bearing  worms  (Fig.  140),  on  account 
of  their  general  resemblance  to  those  long-suffering 
creatures  which  he  in  his  youth  impaled  on  a  hook  and 
with  them  sought  the  nearest  water.  The  extensive 
bristles  of  the  aquatic  worms  are  an  addition  which 
greatly  lessen  their  resemblance  to  the  common  earth- 
worm, and  their  transparency  is  another  characteristic 
that  may  temporarily  mislead  the  observer,  but  their 
elongated  bodies  and  general  worm-like  aspect  tell  the 
story.  In  addition  to  the  bristles  which  most  members 
of  this  class  possess,  there  are  usually  two  or  more 
rows  of  long,  curved  spines  (Fig.  141)  on  the  ventral  or 
lower  surface.  These  can  be  protruded  or  withdrawn 
into  the  body  at  the  possessor's  will,  and  when  pro- 
truded are  used  to  assist  the  worm  to  crawl.  They  are 
therefore  called  the  podal  or  foot  spines.  They  may 
not  be  noticed  when  retracted  unless  specially  searched 
for.  Having  observed  them  and  the  bristles  in  a  row 
on  each  side  above  them,  the  student  need  have  no  trou- 
ble in  knowing  where  to  class  the  worms ;  but  with  an- 
8* 


164  MICROSCOPY  FOll  BEGINNERS. 

other  division  of  the  group  the  beginner  may  not  fare 
so  well. 

These  have  flattened,  usually  almost  opaque  bodies, 
with  the  entire  surface  densely  clothed  by  fine  cilia, 
and,  probably  on  account  of  the  stir  and  disturbance 
which  the  cilia  make  in  the  water,  naturalists  have 
classed  the  worms  together  under  the  name  of  the  Tur- 
lelldria,  from  a  Latin  word  meaning  a  stir  or  bustle. 
Their  motions  are  rapid,  and  apparently  without  effort. 
They  glide  smoothly  and  swiftly  over  submerged  objects, 
or  swim  back  downward  on  the  surface  of  the  water. 

There  is  still  another  group  of  common  aquatic 
worms,  but  to  recognize  them  will  give  even  the  begin- 
ner very  little  trouble.  They  are  often  rather  sluggish 
in  their  movements.  They  have  a  perfectly  transparent, 
smooth,  thread-like  body,  which  is  apparently  truncate 
in  front,  and  is  prolonged  posteriorly  in  a  sharpened, 
point-like  tail.  They  have  no  bristles  nor  cilia,  and  they 
rather  closely  resemble  a  microscopic  eel ;  indeed  the 
scientific  name,  Anguillula  means  a  little  eel. 

Many  members  of  all  these  classes  are  found  in  the 
superficial  sediment  of  shallow  ponds,  in  the  crevices  of 
wet  and  water -soaked  logs,  under  submerged  stones, 
among  the  leaflets  of  Myriophyllum,  Sphagnum,  and 
other  water-plants.  Sphagnum  seems  a  favorite  place 
for  several  kinds.  I  have  obtained  members  of  five 
genera,  Ndis,  Pristina,  Dero,  Chcetogdster,  and  ^Eolo- 
soma,  by  placing  a  little  piece  of  the  moss  in  a  watch- 
glass  with  a  small  quantity  of  water,  and  gently  tearing 


SOME  AQUATIC  WORMS,  ETC.  165 

away  the  leaves  with  needles,  when  the  concealed  worms 
hurried  out  and  were  readily  captured  with  the  dip- 
ping-tube. If  the  watch-crystal  stands  on  black  paper 
the  work  is  facilitated,  as  the  translucent  worms  then 
appear  to  the  naked  eye  as  minute,  writhing,  silvery 
threads. 

In  this  chapter  the  reader  will  also  find  descriptions 
of  two  very  common  microscopic  aquatic  animals,  one 
of  which  is  certainly  not  a  worm,  the  proper  position  of 
the  other  being  rather  doubtful.  They  are  Chcetonotus 
and  Chironomus  larva  (Figs.  131, 132),  both  having  some- 
what worm-like  bodies.  They  are  here  referred  to  for 
the  convenience  of  both  reader  and  writer.  The  begin- 
ner will  be  quite  sure  to  at  first  mistake  Chironomus 
larva  for  a  worm. 

The  bodies  of  all  the  worms  are  very  soft  and  easily 
injured.  It  is  best,  therefore,  in  studying  them  to  use 
a  cell  shallow  enough  to  somewhat  restrain  their  move- 
ments, when  the  cover-glass  is  added,  but  deep  enough  to 
avoid  undue  pressure,  or  they  wrill  rapidly  go  to  pieces. 

The  following  Key  will  assist  the  beginner  in  deter- 
mining to  which  class  his  worm  may  belong,  leading  to 
the  names  of  the  groups  under  which  some  of  their 
generic  titles  may  be  found  : 

1.  Body  with  four  leg-like  appendages  bearing  hooked 

bristles ;  eyes  distinct ;  head  large,  brownish  -  red. 
Chironomus  larva,  I. 

2.  Body  without  leg-like  appendages  (a). 

a.  Tail  forked ;  mouth  small,  circular,  on  the  front 


166  MICROSCOPY  FOR  BEGINNERS. 

part  of  the  lower  or  ventral  flat  surface ;  back 
convex,  usually  bearing  spines,  prickles,  or  scales. 
Chcetonotus,  II. 

a.  Tail  not  forked,  but  often  bearing  finger-like  ap- 
pendages (J). 

5.  Body  entirely  and  finely  ciliated,  usually  flattened. 

Turbelluria,  III. 

6.  Body  smooth,  without  cilia,  bristles,  or  spines ;  tail 

pointed.    Anguillula,  IV. 

&.  Body  with  bristles,  podal  spines,  or  both.     Oligo- 
chceta,  V. 

I.  CHIRONOMUS  LARVA  (Fig.  131). 

Chironomus  larva  has  a  worm -like,  more  or  less 
jointed,  colorless  body,  eight  or  nine  times  as  long  as 
wide,  a  large  head,  the  mouth  parts  usually  being  dis- 
tinctly apparent.  The  four  short  rudimentary  leg-like 
appendages  are  in  pairs  on  each  end  of  the  long  body, 
the  brownish  hooks  or  strong  curved  bristles  on  their 
extremities  being  more  or  less  retractile,  while  two  clus- 
ters of  long  bristles  spring  from  the  upper  surface  near 
the  posterior  border  of  the  animal.  The  perfect  in- 
sect into  which  this  larva  will  develop  is  a  two-winged 
fly  resembling  a  mosquito.  These  are  often  seen  in 
great  numbers  above  the  ponds  and  marshes.  The  spe- 
cies are  very  numerous,  and  have  never  been  studied  by 
American  entomologists. 

The  eggs  are  very  common  on  sticks,  floating  chips, 
or  other  objects  in  the  water.  They  are  deposited  in  ft 


SOME  AQUATIC  WORMS,  ETC.          167 

mass  of  jelly,  huge  in  bulk  when  compared  with  the 
size  of  the  insect,  the  eggs  appearing  as  distinct  but 
minute,   often   brownish, 
specks,  arranged  in  beauti- 
fully regular  rows. 

It  is  always  interesting 
as  well  as   important  for 

the  collector  to  take  home         Pig  13K_Chil.6nomus  larva. 
all  the  little  jelly-like  egg 

masses  which  he  may  find  attached  to  submerged  objects. 
If  placed  in  a  watch-glass  or  an  "individual"  butter-dish, 
and  the  water  kept  fresh  and  pure,  they  will  usually 
hatch,  and  thus  give  the  observer  valuable  information 
often  not  otherwise  obtainable.  Chironomus  eggs  can 
hardly  be  described  so  that  the  beginner  shall  recognize 
them  at  first  glance,  but  if  once  hatched  at  home  they 
will  afterwards  always  be  known.  The  first  little  mass 
of  jelly  experimented  with  may  prove  to  be  snails'  eggs, 
but  they  will  be  none  the  less  interesting.  They  may 
also  prove  to  be  the  eggs  of  water-mites  (Chapter  XI.). 
The  beginner  will,  of  course,  not  mistake  the  green  jelly 
globules  of  Chaetophora  for  insect  eggs. 

II.  CILETONOTCS  (Fig.  132). 

There  are  several  species  of  these  lithe  and  graceful 
little  creatures  in  our  fresh  waters,  and  they  so  closely 
resemble  each  other  in  external  form  that  they  can 
be  distinguished  only  by  the  cuticular  appendages,  or 
the  coat-of-mail  by  which  most  of  them  are  protected. 


168  MICROSCOPY  FOR  BEGINNERS. 

They  are  readily  to  be  found  by  fishing  for  them  with 
a  dipper,  as  recommended  for  Rhizopods.  as  they  are 
fond  of  gliding  over  the  soft  ooze  at  the  bottom  of  shal- 
low ponds.  If  the  collector  will  also  sweep  his  dipper 
under  the  lily  leaves  and  among  the  submerged  stems 
of  Nuphar,  he  will  not  be  disappointed. 

The  animal  consists  of  a  free-swimming,  flexible,  and 
elongated  body,  the  anterior  extremity  usually  enlarged 
to  form  what  may  be  called  the  head,  a  slight  constric- 
tion behind  this  part  constituting 
the  neck;  the  central  portion  of 
the  body  is  formed  with  convex 
Fig.i32.— chsetonotusiarns.  lateral  borders  and  a  more  or  less 
strongly  convex  back  or  dorsum, 
this  region  being  variously  appendaged  with  spines  or 
scales,  and  suddenly  narrowed  to  produce  the  posterior  ex- 
tremity, which  is  forked,  and  bears  two  conspicuous  tail- 
like  prolongations.  The  lower  or  ventral  surface  is  a  flat 
and  nearly  level  plane  extending  the  entire  length  of  the 
body.  It  bears  one  longitudinal  band  of  cilia  near  each 
lateral  border,  seldom  more.  The  head  is  usually  some- 
what triangular,  and  formed  of  three  or  five  rounded 
lobes.  It  has  two  tufts  of  vibratile  hairs  on  each  side. 

The  mouth  is  on  the  ventral  surface  of  the  head,  and 
under  a  moderate  amplification  seems  to  be  a  circular 
opening,  but  with  an  objective  of  high  power  it  will  be 
found  to  be  somewhat  complicated. 

The  whole  upper  surface  of  the  body  is,  in  the  differ- 
ent species,  covered  with  rounded  papillae,  scales,  spines, 


SOME  AQUATIC  WORMS,  ETC.          169 

or  prickles,  or  with  both  scales  and  spines  at  the  same 
time.  In  the  latter  kinds  the  scales  cover  the  back  and 
sides,  and  the  spines  spring  from  these  appendages,  arch- 
ing back  towards  the  forked  tail.  And  in  all  cases  these 
little  scales  are  imbricated,  or  overlapping  like  the  shin- 
gles on  a  roof,  only  they  have  the  curious  habit  of  lap- 
ping in  what  seems  to  be  the  wrong  way,  that  is,  their 
free  margins  point  towards  the  animal's  head,  or  in  a 
direction  just  opposite  to  that  of  the  scales  on  a  fish. 
They  are  usually  minute,  and  require  high  powers  to 
see  them  properly. 

The  two  caudal  prolongations  are  movable  and  flexi- 
ble. Their  chief  use  seems  to  be  to  anchor  the  animal 
to  the  glass  slide  or  cover,  or  to  some  object  in  the  wa- 
ter, clinging  with  the  tips,  and  apparently  assisted  by 
a  secretion  that  is  supposed  to  exude  from  them,  this 
sticky  fluid  passing  from  two  ovate  glands  usually  visi- 
ble in  the  upper  or  anterior  part  of  each. 

The  mouth  opens  into  a  very  muscular  oesophagus, 
which  itself  opens  into  the  intestine,  a  tapering,  tubular 
passage  lined  with  nucleated  cells  and  passing  in  almost 
a  straight  course  along  the  median  line,  terminating  be- 
tween the  two  caudal  prolongations.  If  the  observer 
can  get  the  animal  in  such  a  position  that  he  can  focus 
down  on  the  front  of  the  head,  he  will  see  that  the  cav- 
ity of  the  oesophagus  is  triangular.  It  is  not  very  diffi- 
cult to  do  this,  since  the  little  creatures  are  exceeding- 
ly restless;  they  are  continually  turning  and  writhing 
about,  and  lifting  the  head  in  various  directions.  It  can 


170  MICROSCOPY  FOR  BEGINNERS. 

often  be  seen  in  the  animal  while  still  in  the  egg,  for 
even  there,  when  almost  ready  to  escape,  it  is  also  very 
restless.  The  eggs  are  often  found  on  the  slide,  with 
the  young  Chsetonotus  doubled  up  within. 

The  eggs  by  which  Chsetonotus  is  reproduced  are 
formed  in  an  ovary  placed  in  the  median  line  of  the 
body  immediately  above  the  intestine.  Usually  only 
one  egg  is  formed  at  a  time,  but  it  is  not  rare  to  see  two 
or  more  in  various  stages  of  ovarian  development.  Upon 
the  absence  or  presence  of  an  egg  in  the  ovary  depends, 
to  a  great  extent,  the  degree  of  convexity  of  the  back. 
The  eggs  are  dropped  anywhere  in  the  water,  and  left 
to  the  care  of  nature. 

The  food  consists  of  the  minute  particles  of  decayed 
animal  and  vegetable  matters  so  abundant  in  the  soft 
surface  of  the  mud  at  the  bottom  of  our  shallow  ponds. 
These  particles  are  taken  in  with  a  peculiar  and  a  sud- 
den snapping  movement  of  the  cavity  of  the  oesophagus, 
easily  to  be  seen  but  difficult  to  describe.  Diatoms  are 
rarely  swallowed. 

So  far  as  their  classification  is  concerned,  these  attract- 
ive little  animals  have  given  naturalists  a  good  deal  of 
trouble.  Some  have  said  that  they  belong  with  the 
Rotifers ;  others  have  placed  them  among  the  Infuso- 
ria ;  others  have  called  them  low  worms,  putting  them 
among  the  Turbellaria ;  and  still  others  think,  and  they 
are  doubtless  correct,  that  Chsetonotus  should  stand  in  a 
group  by  itself,  among  the  worms,  and  not  very  far  from 
the  Rotifers. 


SOME  AQUATIC  WORMS,  ETC.         171 

They  are  all  rapid  swimmers,  and  on  that  account  are 
rather  difficult  to  study,  but  by  following  one  for  a 
little  while,  it  will  usually  settle  down  and  begin  to 
seek  food,  and  that  is  the  observer's  opportunity,  un- 
less he  desires  to  kill  the  specimen,  and  study  it  after 
death. 

The  following  Key  leads  to  some  of  our  common 
forms : 

Key  to  Species  of  Ckcetonotus. 

1.  Upper    surface   with   neither  spines,  prickles,  nor 

scales  (a). 

2.  Upper  surface  bearing  scales  only  (b). 

3.  Upper  surface  bearing  spines  or  prickles  only  (c). 

4.  Upper  surface  bearing  both  spines  and  scales  (/). 

5.  Upper  surface  bearing  posterior  spines  and  anterior 

prickles  (g). 

a.  Back  smooth  and  naked,  not  furrowed,  podura,  1. 
a.  Back  transversely  furrowed,  sulcdtus,  2. 

a.  Back  covered  with  small  hemispherical  elevations, 

condnnus,  3. 

b.  Caudal  branches  of  moderate  length,  scales  round- 

ed, loricdtus,  4. 

b.  Caudal  branches  very  long  and  jointed ;  scales  very 

small,  rhombic,  rhomboides,  5. 

c.  Spines  covering  the  entire  upper  surface  (d). 

c.  Spines  not  covering  the  entire  upper  surface  (e). 

d.  Spines  long,  mouth  beaded,  mdximus,  6. 

d.  Spines  short,  mouth  not  beaded,  Idrus,  7. 

e.  Spines  eight,  in  two  longitudinal  rows   of  three 


172  MICROSCOPY  FOR  BEGINNERS. 

each,  with  one  anterior  and  one  posterior  central 
spine,  octondrim,  8. 

e.  Spines  in  two  transverse  rows,  not  projecting  be- 
yond the  ends  of  the  caudal  branches,  spino- 
sulus,  9. 

e.  Spines   in  two  transverse,  highly  -  arching  rows, 

the  posterior  longest  and  projecting  beyond 
the  ends  of  the  caudal  branches,  longispinosus, 
10. 

f.  Back  with  a  subcentral,  transverse  hedge  of  large 
spines,  scales  double,  acanthodes,  11. 

f.  Back  without  a  distinct  spinous  hedge,  scales  not 

double,  spinifer,  12. 

g.  Spines  in  four  transverse  rows,  five  spines  in  each, 

acanthophorus,  13. 

g.  Spines  in  transverse  rows,  less  than  five  spines  in 
each,  enormis,  14. 

1.  CHITON  OTUS  PODURA. 

Clicetonotus,  or  bristle-back,  is  rather  a  misnomer  for 
a  species  with  a  perfectly  smooth  dorsum,  yet  such  a 
one  is  not  uncommon.  The  spines  and  other  dorsal  ap- 
pendages are  here  represented  by  two  hairs  standing  al- 
most vertically  on  the  neck,  and  two  on  the  rear  part  of 
the  back.  These  are  usually  seen  with  difficulty,  but 
they  are  present  on  all  the  species,  even  the  scaly 
and  the  spinous  ones.  The  egg  of  this  species  is 
also  smooth.  Ehrenberg  called  this  Icthydium  po- 
dura. 


SOME   AQUATIC  WORMS,  ETC.  173 

2.  CH^ETONOTUS  STTLCATUS. 

The  characteristic  of  this  form  is  in  the  deep  trans- 
verse furrows  conspicuously  developed  on  the  back  and 
sides.  The  body  is  transparent,  and  unusually  soft  and 
flexible.  The  posterior  region  between  the  arch  of  the 
back  and  the  caudal  furcation  is  narrowed,  and  much 
longer  than  in  other  species.  The  oesophagus  is  short, 
being  not  more  than  one-sixth  the  length  of  the  body. 


COtfCJNNUS. 

The  back  and  sides,  which  are  more  nearly  parallel 
than  in  most  species,  are  closely  covered  by  small  hemi- 
spherical elevations  arranged  in  oblique  lines  and  giving 
the  animal  a  peculiarly  neat  and  attractive  appearance. 
The  two  caudal  glands  are  unusually  large  and  conspic- 
uous. 

4.    Cfl^TOIsOTtTS  LORICATUS. 

The  scales  on  the  back  and  sides  are  arranged  in  im- 
bricated rows,  the  convex  free  margins  being  directed  for- 
ward. Although  so  completely  covered,  the  body  is  very 
flexible,  the  scales  freely  sliding  over  each  other  when 
the  animal  curves  to  one  side.  The  mouth  is  obliquely 
placed,  as  may  be  seen  when  the  Chaetonotus  is  viewed 
in  profile,  and  its  internal  margin  is  strongly  beaded. 
The  eggs  are  armed  by  hollow  papillae,  or  by  short  hol- 
low spines  whose  summits  are  bifid  or  emarginate. 

5.  CHAETONOTUS  KHOMBOIDES. 
This  is  easily  recognizable  by  the  peculiar  head,  the 


174:  MICROSCOPY  FOR  BEGINNERS. 

minute  rhombic  scales  covering  the  back  and  sides,  and 
by  the  remarkably  long  and  jointed  caudal  branches, 
each  of  the  latter  forming  from  one-third  to  one-fourth 
of  the  entire  length  of  the  body.  The  animal  is  the 
largest  yet  discovered,  measuring  -fa  inch  long.  The 
caudal  branches  are  composed  of  about  twenty  sections 
or  joints,  each  of  which  is  slightly  constricted.  The  head 
is  broadly  rounded,  and  formed  of  three  lobes,  one  front- 
al and  two  lateral,  the  former  terminating  on  each  side 
in  a  single,  acuminate,  hook-like  process,  habitually  in 
close  apposition  with  the  anterior  region  of  the  lateral 
lobes,  of  which  the  posterior  extremities  also  terminate 
each  in  a  single  hook-like  continuation,  rather  more  con- 
spicuous than  those  at  the  front.  The  mouth  is  beaded, 
and  has  immediately  behind  it  on  the  ventral  surface  a 
deep,  narrow,  transverse,  and  slit-like  depression,  rather 
less  than  one-half  as  long  as  the  diameter  of  that  part  of 
the  head.  This  is  the  only  known  Chsetonotus  with 
this  problematical  feature. 

The  back  and  sides  are  completely  clothed  by  minute, 
imbricated,  rhombic  scales,  their  front,  pointed  margins 
being  directed  towards  the  head.  They  are  not  more 
than  y^  inch  in  length,  and  when  examined  with  a 
high  power  (one  thousand  diameters)  they  present  a 
beautiful  appearance.  The  lateral  margins  then  seem 
to  be  thickened,  and  the  posterior  border  of  each  scale 
appears  to  bear  a  minute  supplementary  scale  in  the 
shape  of  a  triangle. 

Although  the  beginner  may  not  be  able  to  distinctly 


SOME  AQUATIC  WORMS,  ETC.          175 

see  these  scales,  the  very  long  caudal  branches  with 
their  joints,  and  the  sulcation  behind  the  mouth,  will  be 
sufficient  to  identify  the  specimen. 

6.  CELETONOTUS  MAXIMUS. 

The  back  and  sides  are  covered  with  spines  which  are 
often  rather  longer  on  the  posterior  region  than  else- 
where. They  are  arranged  in  longitudinal  parallel  rows, 
yet  they  often  seem  to  be  irregularly  scattered,  so  that 
the  animal  presents  an  untidy,  dishevelled,  and  disrep- 
utable appearance.  The  spines  are  minutely  forked 
near  the  free  ends.  The  branching  is  very  uneven  and 
is  easily  overlooked,  one  branch  being  very  small,  often 
scarcely  more  than  a  minute  linear  projection. 

The  ventral  cilia  are  in  two  longitudinal  lateral  bands, 
and  the  space  between  is  clothed  with  short,  hispid,  re- 
curved hairs,  two  or  more  long  fine  bristles  projecting 
from  the  same  part  beyond  the  posterior  border,  be- 
tween the  two  caudal  branches. 

7.    ClLETONOTUS  LAKTJS  (Fig.  132). 

The  whole  upper  surface  is  clothed  with  short,  conical 
spines  in  longitudinal  rows,  these  appendages  being  re- 
curved and  not  branched.  They  are  often  largest  pos- 
teriorly. The  mouth  is  not  beaded.  The  ventral  cilia 
are  in  two  broad  longitudinal  bands  near  the  lateral  mar- 
gins, and  the  intervening  space  often  bears  two  addi- 
tional parallel  lines  of  cilia,  which  may  be  absent  from 
some  specimens.  These  cilia,  as  in  all  the  species,  sub- 


176  MICROSCOPY  FOR  BEGINNERS. 

serve  locomotion.     The  egg  is  smooth,  or  hispid  with 
short  hairs. 

8.  Cn^ETONOTUS  OCTONARIUS. 

This  is  a  small,  active  form,  readily  recognizable  by 
the  arrangement  of  the  recurved  dorsal  spines.  These 
are  unequally  branched,  and  placed  in  two  lateral  lon- 
gitudinal rows  of  three  spines  each,  with  one  anterior 
and  one  posterior  central  thorn.  It  seems  to  be  the 
least  common  of  the  species. 

9.  CH^ETONOTUS  SPINOSULUS. 

The  back  usually  bears  seven  unequally  furcate  spines 
in  two  transverse  rows — four  spines  in  the  anterior  series, 
three  in  the  posterior.  Occasionally  the  lateral  thorns 
in  the  posterior  row  are  suppressed,  and  fn  some  indi- 
viduals the  front  series  contains  but  three.  The  lateral 
body-margins  are  bordered  by  short,  conical  setae,  which 
are  constant  in  all  the  specimens  thus  far  observed.  The 
rest  of  the  upper  surface  is  without  appendages  of  any 
kind,  except  the  four  tactile  vertical  bristles  present  in 
all  species.  The  egg  is  hispid  with  short  hairs. 

10.    Cn^ETONOTUS  LONGISPINOSUS. 

The  spines  vary  from  four  to  eight,  the  latter  being 
the  usual  complement.  They  are  nearly  one-half  the 
length  of  the  body,  and  curve  upward  and  backward  in 
a  wide  arch  from  the  centre  of  the  back.  In  front  of 
the  anterior  row  the  surface  is  setose  with  stiff,  recurved 
bristles,  and  the  body- margins  are  fringed  by  coarse, 


SOME  AQUATIC  WORMS,  ETC.          177 

rigid  setae.  The  dorsal  spines  are  always  in  two  trans- 
verse rows,  but  the  number  varies  from  four  in  each  to 
three  in  one  and  five  in  the  other.  They  are  unequally 
furcate. 

11.  CH^ETONOTUS  ACANTHODES. 

The  upper  surface  of  this  form  is  wondrously  well 
protected.  It  possesses  both  spines  and  scales,  the  lat- 
ter imbricated,  and  their  somewhat  pointed  free  margins 
directed  forward,  each  one  bearing  a  small  supplement- 
ary scale  or  scale-like  thickening  on  its  posterior  part, 
from  which  springs  a  recurved,  unequally  furcate  spine. 
Near  the  body-centre  the  dorsal  surface  is  traversed  by 
a  series  of  large  stout  spines  rising  obliquely  upward 
and  backward,  and  forming  a  kind  of  spinous  hedge, 
the  surface  behind  these  appendages  bearing  few  small 
conical  thorns  or  none.  The  body  margins  are  fringed 
by  short  spines.  The  central  space  on  the  ventral  as- 
pect between  the  two  longitudinal,  lateral  bands  of  cilia, 
is  beset  with  short,  fine,  recurved  prickles,  and  five  or 
more  long  bristles  project  from  the  same  surface  beyond 
the  border  of  the  posterior  bifurcation,  while  on  each 
side  of  the  body  near  the  posterior  extremity  there  are 
two  large  recurved  spines.  The  animal  is  usually  found 
among  Sphagnum. 


12.    Cn^ETONOTUS  SPfNIFER. 

Among  Riccia  and  Lemna  in  shallow  ponds  this 
well-armored  form  is  not  rare.  The  upper  surface  is 
covered  by  rounded  imbricated  scales,  the  free  margins 


178  MICROSCOPY  FOR  BEGINNERS. 

directed  forward.  From  each  scale  there  arises  a  stout, 
recurved,  unequally  and  minutely  furcate  spine,  whose 
base  is  enlarged  and  thickened.  These  spines  do  not 
commonly  originate  from  the  centre  of  the  scales,  but 
near  the  posterior  part,  and  between  the  margins  of 
those  laterally  contiguous.  The  spines  are  largest  and 
stoutest  on  the  back  proper,  decreasing  gradually  over 
the  neck  and  head,  and  rapidly  over  the  posterior  parts, 
while  across  the  dorsal  surface  immediately  in  front  of 
the  caudal  bifurcation  there  extends  a  supplementary 
series  of  four  thorns,  longer  and  stouter  than  those  on 
any  other  part  of  the  body.  The  posterior  region  of 
the  space  between  the  longitudinal  ventral  bands  of 
cilia  bears  five  bristles,  arranged  to  form  a  long  triangle, 
the  apex  pointing  forward. 

The  eggs  vary  considerably  in  external  ornamenta- 
tion, showing  three  patterns.  In  one,  the  ends  and  one 
side  bear  low,  stout,  hollow  processes,  whose  apices  are 
truncate,  and  four  or  five  parted  when  viewed  from 
above.  In  another,  the  appendages  are  long,  hollow, 
conical  spines,  whose  distal  ends  are  trifid  or  quadrifid, 
the  branches  in  profile  appearing  very  fine  and  delicate, 
but  when  viewed  from  above  are  seen  to  taper  to  the 
ends,  where  each  terminates  in  a  widely  spreading  fur- 
cation. In  the  third  form,  one  side  and  both  ends  are 
covered  by  an  irregular  net -work  of  raised  lines,  the 
meshes  being  four  or  five  angled,  while  the  opposite 
side  is  rugose  with  fine,  minutely  sinuous  lines. 


SOME  AQUATIC  WORMS,  ETC.  179 

13.  CH^ETONOTTJS  ACANTHOPHORUS. 

The  superior  surface  of  the  head  and  neck  and  the 
lateral  body-margins  are  clothed  with  recurved  prickles 
or  short  spines,  while  the  dorsal  region  proper  bears 
four  rows  of  long  thorns,  each  row  curved  towards  the 
head,  and  each  formed  of  five  unequally  furcate  spines, 
with  an  additional  one  on  both  sides  near  the  posterior 
extremity.  The  spines  rise  from  an  enlarged  base,  so 
that  the  animal  is  almost  completely  clothed  in  an  armor 
composed  of  these  basal  enlargements. 

14.    ClLETONOTUS  ENORMIS. 

The  upper  and  lateral  surfaces  of  the  head  and  neck 
are  clothed  with  short,  recurved  prickles,  which  also  ex- 
tend along  the  ventro-lateral  margins.  The  central  and 
posterior  parts  of  the  back  bear  thirteen  posteriorly  di- 
rected, but  only  slightly  curved,  spines  arranged  in 
transverse  rows,  with  three  in  the  first  row,  four  in  the 
next  following,  two  widely  separated  in  the  third,  three 
in  the  fourth,  while  the  fifth  series  consists  of  a  single 
centrally  located  one.  On  each  side  near  the  posterior 
margin  are  two  long,  conspicuous,  and  recurved  thorns, 
apparently  belonging  to  the  series  of  small  spines  fring- 
ing the  lateral  body-margins. 

III.  TURBELLARIA. 

The  ciliated  or  Turbelldrian  worms  seem  to  prefer 
the  bottom  of  shallow  ponds,  probably  because  the  food- 
supply  there  is  better  and  more  easily  obtained.    They 
9 


180  MICROSCOPY  FOR  BEGINNERS. 

are  soft  and  flexible,  and  some  are  quite  changeable  in 
shape,  having  the  power  to  lengthen  themselves,  to  ex- 
tend the  posterior  border  into  a  short  projection,  or  to 
narrow  the  front  into  an  apology  for  a  head.  Some, 
however,  have  the  front  part  naturally  prolonged  into  a 
short  snout.  They  are  usually  brownish  and  almost 
opaque,  the  opacity  being  increased  by  the  large  amount 
of  food  commonly  present  in  the  stomach. 

The  cilia  clothing  the  entire  surface  are  visible  only 
under  a  high  power.  The  result  of  their  motion,  how- 
ever, can  be  seen  with  the  one -inch  objective,  as  they 
produce  currents  in  the  water  that  sweep  small  objects 
quite  rapidly  away. 

Two  or  more  small  black  or  reddish  eye -spots  are 
often  present  near  the  front  border,  and  in  some  of 
these  worms  may  be  quite  complicated  in  structure, 
having  a  covering  that  may  not  inappropriately  be 
called  a  cornea,  a  refracting  body  corresponding  to  a 
crystalline  lens,  pigmentary  or  coloring  matter,  and  a 
nerve. 

The  position  of  the  mouth  varies  widely  in  the  differ- 
ent families.  It  may  be  at  or  near  the  front  border,  at 
some  point  nearer  the  centre  of  the  body,  or  even  close 
to  the  posterior  margin.  It  is  usually  large  and  expan- 
sile, and  is  often  followed  by  a  large  and  very  muscular 
organ  called  the  pharynx,  which  some  of  the  worms  can 
protrude,  and  with  it  snap  up  their  living  prey.  The 
lining  of  the  pharynx  may  be  finely  ciliated. 

The  stomach  occupies  the  largest  portion  of  the  body, 


SOME  AQUATIC  WORMS,  ETC.         181 

usually  extending  from  the  pharynx  to  the  posterior 
border.  In  some  it  is  simply  a  great  sack,  receiving  all 
that  the  mouth  and  pharynx  turn  into  it ;  in  others  it 
divides  into  many  branches  whose  terminations  may  be 
seen  near  both  sides  of  the  body.  The  stomach  seldom 
has  a  posterior  opening,  for,  as  a  rule,  there  is  no  intes- 
tine. After  the  nutriment  has  been  digested  from  the 
food,  the  insoluble  remains  must  be  ejected  through  the 
mouth.  It  is  no  unusual  sight  to  see  one  of  these  ciliat- 
ed worms  vomit  up  a  mass  of  indigestible  and  empty 
Ehizopod  shells,  Eotifer  carapaces,  with  many  unrecog- 
nizable particles  and  fragments.  They  seem  to  prefer 
animal  food,  usually  selecting  Rhizopods  and  Rotifers, 
but  they  are  as  fond  of  Infusoria,  which  must  be  as 
nourishing  and  more  easily  digested.  I  have  more  than 
once  lost  an  interesting  specimen  of  Infusorium  because 
one  of  these  Turbellarian  worms  had  been  included  un- 
der the  cover-glass :  there  were  a  worm  and  an  Infuso- 
rium ;  a  pause,  a  single  snap,  and  only  the  worm  re- 
mains. 

They  are  propagated  in  two  ways  —  by  eggs  and  by 
transverse  fission ;  that  is,  one  worm  divides  across  the 
middle  and  so  makes  two,  each  of  these  again  dividing. 
And  often  before  the  division  has  been  accomplished 
both  halves  are  also  partly  divided,  so  that  the  single 
body  seems  to  be  formed  of  several  incomplete  worms. 
The  eggs  of  the  commonest  species  are  brownish  egg- 
shaped  bodies,  dropped  anywhere  in  the  mud  or  water, 
or  they  may  have  a  stem  which  attaches  them  to  sub- 


182  MICROSCOPY  FOR  BEGINNERS. 

merged  objects,  and  from  which  they  are  easily  broken. 
The  latter  kinds  are  readily  recognized,  being  formed  of 
a  yellowish  brown,  transparent  membrane,  egg-shaped, 
and  with  the  stem  almost  equalling  their  own  length. 
If  the  observer  be  fortunate  he  may  see  the  worm  es- 
cape by  pushing  off  the  top  of  the  egg,  which  falls  away 
like  a  round  cover,  leaving  an  empty  case  shaped  like  a 
deep  cup.  These  empty  vases  are  often  found  at  the 
bottom  of  long-standing  collections  of  plants. 

The  Turbellarian  worms  are  very  common,  but  the 
beginner  can  scarcely  hope  to  learn  the  generic  name 
of  each  one  that  he  may  find.  He  will  be  safe,  however, 
if  he  refers  to  them  all  as  Tnrbellarians,  or  Turbellarian 
worms.  The  subject  has  not  been  studied  very  exten- 
sively by  American  naturalists,  and  there  is,  consequent- 
ly, nothing  in  the  language  to  which  the  beginner  can 
be  referred  for  help. 

The  worms  are  often  visible  to  the  naked  eye  as 
minute  whitish  or  flesh -colored  floating  bodies,  or  as 
small  bits  of  white  thread.  There  are  two  forms  fre- 
quently met  with  which  are  huge  when  compared  with 
most  of  these  ciliated  creatures,  needing  no  microscope 
to  identify  them.  Both  are  found  on  the  lower  sur- 
faces of  submerged  stones  or  sticks,  or  gliding  over  the 
sides  of  the  collecting-bottle. 

The  body  of  one  of  these  may  be  about  half  an  inch 
in  length  and  about  five  times  as  long  as  broad.  It  is 
opaque  and  almost  black.  Near  the  anterior  border  are 
two  black  eyes,  which  are  conspicuous  on  account  of  the 


SOME  AQUATIC  WORMS,  ETC.  183 

oblong  white  space  in  front  of  each.  The  mouth  is  near 
the  centre  of  the  body,  opening  on  the  lower  or  ventral 
surface.  The  worm  glides  smoothly  and  quite  rapidly 
over  a  submerged  surface.  Naturalists  have  named  it 
Plandria  torva. 

The  second  one  referred  to  somewhat  resembles  Pla- 
ndria torva,  but  is  usually  smaller,  and  has  the  head  end 
more  nearly  triangular.  It  is  similar  in  its  movements 
and  in  the  presence  of  two  black  eyes  near  the  front 
border,  each  at  the  inner  margin  of  a  white  space,  thus 
giving  the  \vorm  a  cross-eyed  appearance.  The  body  is 
nearly  white,  and  has  a  dark  line  passing  lengthwise 
through  the  centre  and  giving  off  on  both  sides  many 
short  branches  which  are  themselves  often  branched, 
these  dark  lines  on  the  white  body  giving  the  latter  a 
very  pretty  appearance.  They  are  not  for  ornament, 
however,  but  are  the  branching  stomach.  The  mouth 
is  near  the  centre  of  the  lower  surface.  The  body  may 
measure  half  an  inch  in  length.  It  has  been  named 
Drendoco&lum  Idcteum. 

The  entire  surface  of  both  these  worms  is  finely  and 
closely  ciliated.  The  color  of  the  body  will  at  once  in- 
form the  observer  which  one  he  has  captured. 

IV..ANGUILLULA  (Fig.  133) 

The  body  is  thread-like,  perfectly  transparent  and 
colorless,  about  fifteen  times  as  long  as  broad,  rather 
widest  in  the  middle,  whence  it  slightly  tapers  towards 
both  ends.  The  frontal  border  is  rounded,  but  with  a 


184  MICROSCOPY  FOR  BEGINNERS. 

low  power  appears  as  if  truncated.  The  round  mouth 
is  at  the  centre  of  this  end,  and  leads  into  an  oblong 
pharynx  or  throat.  The  tail  is  usually  long  and  sharply 
pointed.  The  worm's  movements  are 
generally  slow  and  deliberate,  but  oc- 


are  reproduced  by  eggs,  one  or  more  often  being  visible 
within  the  transparent  body.  Anguillulse  are  common 
in  wet  moss,  among  the  leaflets  of  aquatic  plants,  and 
in  the  ooze  of  the  ponds. 

The  well-known  "  vinegar-eel  "  is  an  Angnillula  (An- 
guUlula  aceti);  and  the  paste-  worm  (A.  glutinis)  be- 
longs to  the  same  genus.  Some  naturalists  regard  these 
as  the  same  species. 

V.  OLIGOCHJETA. 

The  fresh-water  bristle-bearing  worms  whose  bodies 
are  never  ciliated,  show  more  or  less  distinctly  that  they 
are  formed  of  segments  or  rings.  Each  segment  often 
has  on  both  sides  near  the  back  one  or  more  long,  fine, 
hair-like  bristles  extending  into  the  water,  and  together 
forming  a  row  along  each  side  of  the  worm.  On  the 
lower  surface  there  are  two  or  more  rows  of  thicker, 
inflexible,  and  gracefully  curved  spines,  the  rows  being 
formed  of  clusters  which  have  two  or  more  spines  in 
each,  the  free  end  of  every  one  being  usually  divided 
by  a  deep  notch,  so  that  it  appears  like  a  double  hook, 
the  parts  being  unequal  in  size  and  degree  of  curvature. 
They  are  used  to  assist  the  worm  to  crawl,  and  are 


SOME  AQUATIC  WORMS,  ETC.          185 

therefore  called  podal  or  foot  spines.  They  can  be 
protruded  from  the  body,  or  partially  withdrawn  into 
it,  at  the  animal's  will.  The  long  bristles  are  used  to 
assist  in  swimming.  In  some  of  these  worms  both 
the  bristles  and  the  podal  spines  are  present,  in  others 
one  or  the  other  set  of  organs  may  be  absent. 

The  spines,  which  with  but  few  exceptions  are  pres- 
ent, are  each  gracefully  curved  like  a  long  italic  S,  their 
shape  resembling  the  line  which  artists  have  called  the 
line  of  beauty.  The  free  end,  or  the  one  projecting 
into  the  water,  is  forked  in  a  way  already  described 
(Fig.  141).  The  body  or  shaft  of  the  spine  has,  at  some 
point  of  its  length,  a  globular  enlargement  or  a  shoul- 
der, below  which  the  spine  is  often  much  narrowed. 
These  organs  are  used  by  being  protruded  and  forced 
against  the  surface  over  which  the  worm  is  travelling. 
They  are  arranged  in  a  row  on  each  side  of  the  ventral 
surface,  each  row  being  composed  of  many  clusters,  and 
each  cluster  of  from  two  to  ten  podal  spines.  The  worm 
can  protrude  several  clusters  at  once,  or  two  on  the  op- 
posite sides  of  the  same  segment  or  body-ring,  but  it 
seems  unable  to  extend  them  irregularly. 

The  bristles  are  very  flexible,  and  are  arranged  in  two 
rows  on  the  sides,  near  the  upper  surface,  one  row  on 
each  side.  They  are  usually  much  longer  than  the 
width  of  the  body,  and  may  be  so  arranged  that  there 
are  several  or  only  one  on  each  lateral  margin  of 
the  segment.  They  are  sometimes  accompanied  by  a 
straight  spine  much  shorter  than  the  bristle,  and  pro- 


186  MICROSCOPY  FOR  BEGINNERS. 

jecting  beside  it.  The  free  ends  of  these  rudimentary 
spines  are  occasionally  finely  forked.  The  bristles  are 
absent  in  some  genera. 

The  worms  are  usually  visible  to  the  naked  eye  as 
very  fine  whitish  or  yellowish  threads,  sometimes  an 
inch  or  more  in  length  when  extended.  They  are  found 
abundantly  among  aquatic  plants,  and  in  the  mud  of 
shallow  ponds.  When  allowed  to  remain  in  the  col- 
lecting-bottle they  will  often  make  their  way  to  the 
lighted  side,  where  some  will  form  sheaths  or  protect- 
ive cases  from  various  floating  fragments  or  particles. 

The  mouth  may  be  close  to  the  front  end,  or  some 
distance  back,  since  in  a  few  worms  the  front  border  is 
extended  as  a  long,  flexible  snout.  The  posterior  border 
is  rounded  in  many  forms,  while  in  others  it  is  expanded 
into  a  broad,  funnel-like  region,  with  several  finger-like 
prominences  surrounding  it.  In  such  worms  these 
parts  are  ciliated  on  the  inside,  the  currents  thus  pro- 
duced being  supposed  to  bring  at  least  a  portion  of  the 
oxygen  needed  for  respiration.  The  alimentary  canal 
extends  through  the  centre  of  the  entire  body,  and  is 
usually  crowded  with  the  brownish  remains  of  undi- 
gested food.  The  whole  cavity  of  the  body  outside  of 
the  alimentary  canal  is  filled  with  a  colorless  fluid  visi- 
ble only  by  means  of  the  movements  of  the  corpuscles 
seen  floating  to  and  fro  as  the  worm  moves  under  the 
cover-glass. 

The  beginner  must  not  mistake  this  fluid  for  the 
blood,  which  in  many  of  the  bristle-bearing  forms  is  red 


SOME  AQUATIC  WORMS,  ETC.         187 

and  contained  in  two  distinct  vessels,  one  extending 
lengthwise  above,  the  other  below  the  intestine.  These 
vessels  unite  at  both  ends  of  the  body,  so  as  to  form 
a  long,  closed  tube,  with  branches  springing  from  the 
front  part,  or  from  the  upper  or  dorsal  tube  as  it  passes 
through  each  segment,  where  they  then  appear  as  pul- 
sating loops.  Usually  the  blood  is  impelled  by  the  ir- 
regular pulsations  of  the  dorsal  vessel,  a  wave-like  con- 
traction passing  along  and  driving  the  blood  before  it. 
In  two  genera  (Tubifex  and  Ocnerodrilus)  there  are 
little  pulsating  hearts  attached  to  the  dorsal  vessel  in 
the  neighborhood  of  the  frontal  border. 

Eeproduction  is  by  eggs  or  by  tranverse  fission,  the 
latter  being  most  frequently  observed. 

Most  of  these  worms  live  upon  animal  food,  seeming 
to  prefer  Khizopods  and  Rotifers  to  almost  anything 
else ;  a  few  are  vegetarians. 

Key  to  Genera  of  Microscopic,  chiefly  Fresh-water,  Worms 
(  Oligochceta). 

1.  Body  with  both  bristles  and  podal  spines  (a). 

2.  Body  with  podal  spines  only  (J). 

3.  Body  with  bristles  only  (/"). 

a.  Anterior  extremity  with  a  flexible,  finger-like  pro- 
longation.    Pristina,  1. 

a.  Anterior  extremity  without  a  finger-like  prolon- 

gation (d). 

b.  Podal  spines  forked  ;  worms  aquatic  (c). 

I.  Podal  spines  not  forked  ;  worms  aquatic  (g). 
9* 


188  MICROSCOPY  FOR  BEGINNERS. 

J.  Podal  spines  not  forked ;  worms  living  beneath 
decaying  bark  of  dead  trees.  Enchytrceus,  2. 

c.  Podal  spines,  six  to  ten  in  each  cluster,  the  clusters 
in  two  rows.  Chcetogaster,  3. 

c.  Podal  spines,  two  only  in  each  cluster,  the  clusters 

in  four  rows.     Lumbriculus,  4. 

d.  Posterior  extremity  without  finger -like  append- 

ages (e). 

d.  Posterior  extremity  widened,  ciliated,  with  several 
retractile  finger-like  appendages.  Dero,  5. 

d.  Posterior  extremity  ciliated,  with  two  long,  non- 

retractile,  finger-like  appendages.   AuUphorus,  6. 

e.  Bristles  and  podal  spines  in  separate  rows  (A). 

e.  Bristles  and   podal  spines  alternate  in  the  same 

row.     Strephuris,  7. 

f.  Body  variegated  with  brick  red  spots  ;  blood  col- 

orless.    ^Eolosoma,  8. 

g.  Podal  spines  in  clusters  of  four  each ;  body  the 

color  of  raw  meat.     Ocnerodrilus,  9. 

g.  Podal  spines  in  clusters  of  two  each.  Lumbricu- 
lus,  4. 

A.  Worm  with  two  small  anterior  pulsating  hearts ; 
blood  bright  red.  Tubifex,  10. 

h.  Worm  without  a  distinct  heart ;  dorsal  vessel  pul- 
sating; blood  red.  Ndis,  11. 

1.  PmsxfNA  (Figs.  134, 135, 136). 

Body  nearly  cylindrical,  transparent,  often  very  long, 
and  showing  that  it  is  preparing  to  divide  across  the 


SOME  AQUATIC  WORMS,  ETC.          189 

middle  to  form  two  worms.  In  these  cases  the  pro- 
boscis of  the  new  worm  becomes  conspicuous  at  the  cen- 
tre of  the  long  body.  The  mouth  is  near  the 
base  of  the  snout -like  prolongation,  and  this 
narrow  extension  of  the  upper  lip  varies  much 
in  length  in  the  various  species.  The  one  Fi<r  134  _ 
represented  in  Fig.  134  belongs  to  a  common  snout  of  a 
form  in  the  writer's  locality,  and  is  unusually 
long.  The  posterior  extremity  is  commonly  nearly  as 
shown  in  Fig.  135,  and  surrounded  by  many 
short  stiff  hairs,  it  being  the  tail-end  of  the 
Pristina  whose  proboscis  is  shown  in  Fig. 
Fig  135.-POS-  -^  Occasionally  this  part  lias  three  long 

terior  extrem- 
ity of  a  Pns-   trailing  appendages,  as  in  Fig.  136.      The 

blood  is  usually  red.     The  bristles  are  long 
and  fine,  and  are  often  accompanied  by  one 
or  more  short,  nearly  straight,  rudimentary  / flf 

spines.     The  podal  spines  are  in  two  rows  M 

on  the  ventral  surface,  each  cluster  frequent-  |  j| 

ly  containing  as  many  as  eight.      The  pos-    Fig.  m-poste- 

.  *    i       •    ,      i  •         •        fL          'TJ.J          r'or  extremity 

tenor  part-of  the  intestine  is  often  ciliated.      of  a  pristina. 

The  worms  are  found  among  aquatic 
plants,  seeming  especially  fond  of  Sphagnum  and  Lemna 
as  a  home. 

2.  ENCHYTR^EUS. 

The  body  is  white  or  yellowish  white,  thread-like, 
and  from  about  one-half  to  nearly  one  inch  long.  The 
worms  are  found  under  damp  logs  or  beneath  decaying 
bark,  often  in  considerable  numbers.  The  podal  spines 


190  MICROSCOPY  FOR  BEGINNERS. 

are  usually  short,  nearly  straight,  and  not  forked.  The 
blood  is  pale  or  colorless.  There  are  two  species,  which 
are  not  very  difficult  to  distinguish  from  each  other. 

In  one  (Enchytrceus  vermiculdris)  the  body  is  yel- 
lowish white,  and  varies  in  length  from  five-twelfths  to 
eight  -  twelfths  of  an  inch.  The  podal  spines  are  in 
clusters  of  from  three  to  five  spines  each.  This  species 
is  usually  found  under  damp  and  decaying  logs,  and  is 
less  common  than  the  next. 

In  the  second  (E.  socidlis)  the  body  is  opalescent  white 
and  translucent,  varying  from  five  -  twelfths  to  ten- 
twelfths  of  an  inch  in  length.  The  podal  spines  are 
from  five  to  seven  in  each  cluster,  the  anterior  fascicles 
generally  containing  seven,  the  posterior  five.  The 
jnouth  is  triangular.  This  species  is  most  frequently 
found  in  more  or  less  social  groups  beneath  the  moist 
bark  of  old  stumps  or  the  decaying  parts  of  trees,  and 
usually  near  the  ground. 

3.  CH^ETOGASTEK. 

Body  transparent,  often  showing  evidences  of  trans- 
verse fission.  The  podal  Bpines  are  in  two  rows,  the 
clusters  containing  four  to  eight  spines  each,  being 
usually  most  numerous  towards  the  posterior  extremity. 
The  mouth  is  large,  oblique,  and  surrounded  by  many 
very  short  stiff  hairs.  It  is  often  used,  when  the  worm 
is  on  the  slide,  as  a  sticker,  clinging  to  the  glass  and 
drawing  the  body  towards  it.  The  intestine,  in  the 
species  common  in  the  writer's  vicinity,  is  much  and 


SOME  AQUATIC  WORMS,  ETC.  191 

irregularly  constricted,  a  feature  which  gives  it  the  ap- 
pearance of  a  series  of  various  -  sized  pouches.  The 
blood  is  very  pale  or  colorless.  The  blood-vessels  are 
distinct  as  narrow,  pulsating,  longitudinal  tubes.  ChcB- 
togdster  is  one  of  the  most  interesting  forms  on  account 
of  its  perfect  transparency  and  the  absence  of  bristles, 
which  allows  an  uninterrupted  view  of  the  whole  sur- 
face, as  well  as  of  the  internal  organs. 

4.   LUMBKICULUS. 

The  body  is  translucent,  but  often  brightly  colored  at 
the  sides  or  in  the  middle  parts.  The  blood  is  bright 
red,  and  the  dorsal  vessel  gives  off  several  short,  lateral, 
pulsating  branches  in  each  segment  of  the  body.  These 
short  branches  frequently  approach  the  surface,  and  give 
it  a  mottled  appearance,  the  spots  fading  and  reappear- 
ing as  the  branches  contract  and  expand.  There  are 
four  rows  of  podal  spines,  with  but  two  in  each  cluster. 
They  are  curved,  forked  at  the  end,*  and  have  an  en- 
largement or  shoulder  near  their  centre.  At  a  short 
distance  from  the  attached  end  of  each  pair  there  is 
often  to  be  found  another  pair,  which  are  small  and 
may  be  overlooked  on  the  front  of  the  body  when  the 
worm  is  not  dividing  transversely.  When  it  is  under- 
going transverse  fission  the  posterior  part  may  be  so 
well  supplied  with  these  small  secondary  podal  spines 
that  their  number  and  arrangement  may  confuse  the 

*  Since  this  was  written  a  species  has  been  observed  with  undi- 
vided podal  spines.  It  has  been  included  in  the  Key. 


192  MICROSCOPY  FOR  BEGINNERS. 

beginner,  the  rows  then  appearing  to  be  eight,  with 
two  spines  in  each  cluster,  or  four  rows  with  clusters 
of  four  spines  each.  However,  if  the  beginner  will 
examine  the  front  half  of  the  dividing  worm,  and  be 
guided  by  the  podal  spines  there,  he  will  have  little 
trouble  in  recognizing  Lumbriculus. 

5.  DERO  (Fig.  137). 

The  posterior  extremity  is  broad  and  funnel-like,  its 
upper  plane  often  being  oblique.  It  is  finely  ciliated, 
as  are  the  finger-like  projections  and  the  internal  sur- 
face of  the  posterior  part  of  the  intestine,  which  is 
connected  with  it  and  forms  a  portion  of  it.  The  cilia 
produce  currents  over  these  parts  which  are  supposed 
to  absorb  the  oxygen  for  purposes  of  respiration.  The 
finger-like  processes  vary  in  number  from 
two  to  eight.  They  can  be  elongated  or 
drawn  back  into  the  funnel,  which  can  also 
be  retracted  and  almost  closed.  When  ex- 
rior  extremity  tended  they  may  be  much  longer  than  the 


funnel  -like  termination  of  the  body,  or 
they  may  not  reach  to  its  margins.  The  blood  is 
red.  The  podal  spines  vary  from  three  to  five  in  each 
cluster. 

These  worms  are  often  found  on  the  sides  of  the  col- 
lecting-bottle after  it  has  been  standing  for  some  time. 
They  usually  bury  themselves  in  the  mud,  with  the  pos- 
terior part  of  the  body  and  the  expanded  funnel-like  re- 
gion protruded  from  small  mud-chimneys  of  their  own 


SOME  AQUATIC  WORMS,  ETC.          193 

formation.    They  may  measure  half  an  inch  or  more  in 
length. 

6.  AULO'PHOEUS  (Fig.  138). 

The  posterior  extremity  is  not  wider  than  the  width 
of  the  body,  and  the  two  finger -like  appendages  are 
straight  or  slightly  curved.  They  are  blunt,  and  covered 
with  short  stiff  hairs.  The  worm  usually  builds  a  tubu- 
lar sheath  of  various  fragments  and  floating  particles,  in 
which  it  lives,  but  to  the  walls  of  which  it  is  not  ad- 
herent, as  it  frequently  doubles  on  itself,  glides  through 
the  tube,  and  thus  reverses  its  position.  It 
moves  by  jerks,  "  alternately  extending  the 
fore  part  of  the  body  and  projecting  the  FI^.  iss.— POS- 

T    i     r>        •   i         ,>  i  t    i        i  •  •     ,  tcriorextrem- 

podal  fascicles  forward,  and  hooking  into  jtyofanAui6- 
the  surface  on  which  it  is  creeping,  and  Phoru8« 
then  contracting  the  fore  part  of  the  body  and  drag- 
ging along  the  back  part  enclosed  within  the  tube."* 
It  often  helps  itself  along  by  clinging  to  the  slide  by 
its  protruded  throat  or  pharynx.  The  podal  spines  vary 
in  number  from  five  to  nine  in  each  cluster.  The 
fascicles  of  bristles  are  each  accompanied  by  from  one 
to  three  rudimentary  spines,  which  are  nearly  straight, 
and  end  in  a  broadened,  spade-like  expansion.  The  blood 
is  red. 

7.  STREPHURIS  (Fig.  139). 

The  podal  spines  and  bristles  are  arranged  alternately 
with  each  other,  as  in  Fig.  139,  and  together  form  a  single 

*  Dr.  Leidy,  in  the  American  Naturalist,  June,  1880. 


194  MICROSCOPY  FOR  BEGINNERS. 

row  of  clusters  on  each  side  of  the  lower  surface  of  the 
body.  The  spines  are  slightly  curved,  long  and  forked, 
the  bristles  being  three  times  their  length.  The  mouth 
is  triangular.  The  blood  is  bright  red  and  the  vessels 
large.  The  body  is  thread-like,  transparent, 
and  may  be  from  one  to  two  inches  in  length. 
The  front  end  is  whitish,  the  tail  end  yellow- 
ish. It  lives  in  the  mud  beneath  shallow 
Fig.  139.— PO-  water,  and  buries  itself  with  about  two-thirds 
and  bristles  °^  *ne  tail  end  protruding  and  constantly  vi 
or  strephu-  brating.  When  disturbed  it  disappears  into 
its  burrow  with  astonishing  rapidity.  Dr. 
Leidy,  who  discovered  this  curious  creature,  says, "  While 
walking  in  the  outskirts  of  the  city  [Philadelphia]  I  no- 
ticed in  a  shallow  ditch  numerous  reddish  patches  of 
from  one  to  six  inches  square,  which,  supposing  to  be  a 
species  of  alga,  I  stooped  to  procure  some,  when  to  my 
surprise  I  found  them  to  consist  of  millions  of  the  tails 
of  Strephuris  dgilis,  all  in  rapid  movement.  The  least 
disturbance  would  cause  a  patch  of  six  inches  square  so 
suddenly  to  disappear  that  it  resembled  the  movement 
of  a  single  body." 

8.   -2EOLOSOMA. 

The  bristles  are  of  unequal  length,  and  are  arranged 
in  clusters  of  four  bristles  each,  the  clusters  forming  a 
single  row  on  both  sides  of  the  body.  There  are  none 
in  advance  of  the  mouth,  which  is  large  U-shaped,  the 
arms  of  the  TJ  pointing  forward,  the  whole  being  sur- 


SOME  AQUATIC  WORMS,  ETC.          195 

rounded  with  a  thick  border.  The  pharynx  is  broad 
and  ciliated  within.  The  body  is  colorless,  the  brick- 
red  spots  scattered  over  the  internal  surface  giving  the 
worm  a  beautiful  appearance.  ^Eolosoma  is  found  in 
ditches  among  Algae,  on  which  it  feeds.  It  is  not  very 
active  in  its  movements.  The  blood  is  colorless. 

Among  the  Sphagnum  in  the  writer's  locality  there 
not  uncommonly  occurs  a  worm  which  I  have  ventured 
to  identify  as  a  member  of  this  genus.  It  externally 
differs  from  the  species  referred  to  above  in  having 
fewer  and  larger  red  spots,  which  seem  to  be  on  the 
outer  surface  of  the  skin,  where  they  are  most  abun- 
dantly collected  near  the  two  extremities,  being  fewest 
on  the  central  region  of  the  body.  The  bristles  are  so 
arranged  that  they  appear  to  form  two  rows  of  clusters 
on  each  side,  being  separated  into  two  groups  in  each 
cluster.  The  worm  thus  seems  to  have  four  rows  in- 
stead of  the  two,  as  in  the  preceding  species.  Its 
movements  are  also  much  more  active.  It  is  also  a 
vegetarian. 

9.  OCNEBODRILUS. 

This  remarkable  worm  has  thus  far  been  found  only 
in  Fresno  County,  California,  where  it  was  obtained 
among  fine  Algse  growing  to  the  sides  of  a  submerged 
wooden  box,  and  also  occasionally  in  the  mud,  with  a 
part  of  the  tail  end  protruding  and  motionless.  The 
body  is  rather  less  than  an  inch  long,  one-twelfth  of  an 
inch  wide,  and  presenting  the  peculiar  color  mentioned 
in  the  Key.  Its  movements  are  very  slow. 


196  MICROSCOPY  FOR  BEGINNERS. 

The  podal  spines  are  slightly  curved,  but  not  forked 
at  the  ends.  They  are  arranged  in  clusters  of  four 
spines  each,  the  clusters  forming  two  rows,  one  on  each 
side  of  the  body. 

The  O3sophagus  is  long  and  remarkably  muscular.  It 
is  surrounded  and  somewhat  obscured  by  a  pair  of  large 
glands,  and  has  near  its  posterior  extremity  two  large 
appendages  similar  in  structure  to  the  oesophagus  itself. 
The  blood  is  yellowish-red.  The  dorsal  vessel,  at  some 
distance  behind  the  front  end  of  the  body,  divides 
into  three  branches,  which  pass  forward,  and  near  the 
anterior  border  unite  by  means  of  a  net-work  of  fine 
vessels.  The  worm  has  four  hearts,  two  on  each  side  of 
the  dorsal  vessel,  one  pair  being  near  the  eighth,  and 
one  pair  near  the  ninth  cluster  of  podal  spines.  The 
dorsal  vessel  divides  in  front  of  the  first  pair  of  hearts. 
The  ventral  blood-vessel  is  forked,  but  with  only  two 
branches. 

10.  TUBIFEX. 

A  common  and,  in  some  places,  a  very  abundant  little 
worm,  measuring  from  one-half  to  one  and  one-half 
inches  in  length.  The  body  is  thread-like  in  its  nar- 
rowness, and  is  transparent  and  colorless,  although  the 
bright  crimson  blood  gives  it  a  hue  so  vivid  to  the  naked 
eye  that,  where  the  worms  are  numerous,  it  often  seems 
to  tinge  the  mud  in  which  they  live.  They  are  seldom 
found  free-swimming,  but  live  a  comparatively  seden- 
tary life,  with  about  one-half  of  the  body  buried  in  their 
burrow,  the  remaining  parts  protruding  into  the  water, 


SOME  AQUATIC  WORMS,  ETC.  197 

and  constantly  waving  to  and  fro  beyond  the  edge  of 
the  little  tubular  chimneys  which  they  erect.  These 
little  towers  are  often  conspicuous  objects  on  the  sur- 
face of  the  mud  in  shallow  still  water,  the  worms  in- 
stantly disappearing  into  them  at  the  slightest  disturb- 
ance. Among  certain  French  and  German  writers  on 
the  subject,  there  is  a  difference  of  opinion  as  to  which 
end  of  the  worm  is  buried  and  which  end  protrudes  into 
the  water.  As  the  protruding  parts  are  continually 
moving,  and  as  the  worms  also  dart  into  the  mud  with 
such  astonishing  swiftness,  to  decide  the  matter  is  rather 
difficult. 

The  bristles  are  comparatively  short,  and  appear  to 
be  arranged  in  a  single  row  on  each  side  of  the  body, 
whereas  there  is  really  an  additional  row  of  podal  spines 
on  both  sides  of  the  worm.  These  podal  spines  are  en- 
tirely retractile,  and  are  therefore  often  overlooked  un- 
less specially  searched  for.  Even  then  it  will  perhaps 
be  necessary  to  compress  the  worm  rather  forcibly  be- 
tween the  slide  and  the  cover-glass  before  they  will  be- 
come conspicuous.  They  are  forked,  and  but  slightly 
curved. 

With  very  high  magnifying  power  (about  eight  hun- 
dred diameters)  some  of  the  bristles  present  a  curious 
aspect.  The  free  extremity  is  widened  and  forked,  the 
two  prongs  of  the  fork  being  apparently  connected  by  a 
thin  membrane  which  is  longitudinally  striated.  Some- 
times this  membrane  splits  into  fine  hairs.  These  wid- 
ened bristles  are  most  common  on  the  young  worms. 


198  MICROSCOPY  FOR  BEGINNERS. 

The  bright  red  blood  is  contained  in  two  principal 
tubular  vessels,  one  above,  the  other  below  the  tortu- 
ous intestine.  The  upper,  or  dorsal  one,  has  connected 
with  it  near  the  anterior  end  of  the  body  two  little  con- 
tractile hearts,  one  on  each  side,  which  can  be  seen 
through  the  hyaline  animal  throwing  out  the  blood  with 
considerable  force.  The  two  vessels  are  connected  with 
each  other  by  smaller  ones,  a  pair  in  each  segment  or 
body-ring,  one  being  on  each  side.  There  is  also  on 
each  side  of  the  body — two  in  each  segment — a  narrow 
colorless  tube,  ciliated  within,  and  resembling  those 
found  in  Nais  and  other  aquatic  worms.  They  are 
most  conspicuous  in  the  posterior  rings,  and  are  sup- 
posed to  represent  kidneys  in  function. 

Tubifex  is  reproduced  by  eggs,  which  probably  make 
their  escape  after  the  parents'  death,  and  after  the  body 
lias  fallen  to  pieces,  as  the  living  creature  has  no  passage 
for  their  exit.  Huxley,  however,  says  that  they  pass  out 
through  the  segmental  organs — the  ciliated  tubes  just 
referred  to. 

11.  NAIS  (Figs.  140,  141). 

Body  whitish  or  yellowish,  usually  very  active.     The 
podal  spines  and  bristles 
are    each    arranged  in   a 
row  on  both  sides  of  the 
worm,   the    bristles   near 
the  front  end  usually  be- 
ing longest.     Each  cluster  of  podal  spines  contains  four 
or  more.     The  mouth  is  round,  the  front  border  of  the 


SOME  AQUATIC  WORMS,  ETC.  199 

body  bearing  numerous  fine,  short  hairs.  Two  dark  or 
black  eye-spots  are  generally  present,  one  on  each  side 
in  advance  of  the  mouth.  The  blood  is  red.  Many 
narrow,  colorless  tubes,  with  a  ciliated  lining, 
are  to  be  noticed  on  both  sides  of  the  intes- 
tine. They  are  much  looped  and  twisted,  and 
are  supposed  to  play  some  part  in  respiration, 
or  to  represent  the  kidneys  of  animals  higher 
in  the  scale.  They  are  bathed  in  the  color- 
less fluid  filling  the  cavity  of  the  body,  and 
change  their  position  rapidly  as  this  fluid 
flows  to  and  fro,  following  the  movements  of  the  worm. 
Ndis  is  the  commonest  of  the  aquatic  worms,  being 
very  frequently  found  among  Algae  in  shallow  water,  or 
on  the  leaflets  of  various  plants,  especially,  according  to 
the  writer's  experience,  in  Sphagnum,  in  company  with 
Pristina  and  Chaetogaster. 

Dr.  Joseph  Leidy?s  papers,  published  in  the  Journal 
of  the  Academy  of  Natural  Sciences,  Philadelphia,  and 
elsewhere,  are  the  only  ones  to  which  the  student  can 
be  referred  for  further  information  in  connection  with 
the  aquatic  bristle -bearing  worms,  as  Dr.  Leidy  is  the 
only  naturalist  who  has  seriously  studied  the  American 
forms  and  published  the  results  of  his  work. 


200  MICROSCOPY  FOR  BEGES'NERS. 


CHAPTER  VIII. 

KOTIFEKS. 

WHEN  these  transparent  microscopic  animals  are 
swimming  or  taking  food,  there  is  usually  an  appear- 
ance of  two,  small,  rapidly  rotating  wheels  on  the  front 
border  of  the  body,  an  appearance  that  suggested  the 
name  of  Rotifera,  or  Wheel -bearers,  for  the  group. 
The  two  organs  certainly  do  seem  like  rapidly  revolv- 
ing wheels  when  viewed  under  a  low  power,  but  they 
are  in  reality  two  disks  or  lobes  surrounded  by  wreaths 
of  fine  cilia,  which  vibrate  so  quickly  that  the  eye  can 
perceive  the  effect  only.  It  is  by  the  action  of  these 
cilia  that  the  Rotifer  swims  and  captures  food,  the  cur- 
rents produced  by  them  when  the  animal  is  at  rest  set- 
ting in  towards  the  mouth,  usually  situated  between  the 
ciliary  (or  cilia-bearing)  disks,  and  carrying  particles  of 
food  which  the  Rotifer  accepts  or  rejects.  As  a  rule 
the  ciliary  disks  are  two  separate  organs,  but  they  may 
be  united  into  one,  or  the  Rotifer  may  have  the  front 
margin  of  the  body  bordered  by  a  single  line  of  cilia,  or 
the  disks  may  be  entirely  absent,  and  replaced  by  long 
arms,  as  in  Stephanoceros,  or  by  clusters  of  long,  fine 
hairs,  as  in  Flvsculdria,  both  of  which  are  Rotifers. 

Most  of  these  animals  have  eyes  at  some  period  of 
their  life,  or  little  red  specks  supposed  to  be  imperfect 


KOTIFERS.  201 

eyes.  They  are  often  to  be  noticed  near  the  front  of 
the  body  in  young  individuals,  but  in  the  old  they  are 
as  often  absent.  Their  number  and  position  are  some- 
times used  as  characters  by  which  the  genera  and  spe- 
cies are  classified,  but,  since  they  disappear  with  age, 
they  cannot  be  of  much  value  for  this  purpose,  certainly 
not  to  the  beginner. 

The  body  is  inclined  to  be  cylindrical,  yet  there  are 
some  resembling  flat  disks  and  oblong  figures.  Neither 
are  they  all  free-swimming.  Some  are  permanently  ad- 
herent to  the  leaflets  of  aquatic  plants  or  other  sub- 
merged objects,  but  these  generally  form  a  protective 
sheath  about  themselves,  into  which  they  retire  when 
frightened  or  disturbed,  in  a  manner  similar  to  that  of 
some  Infusoria ;  and,  as  in  the  Infusorial  loricse,  the 
sheaths  may  be  formed  of  a  stiff  membrane,  or  of  the 
softest  and  most  gelatinous  material,  or  they  may  be 
built  of  particles  of  dirt  or  rejected  food  fragments.  In 
all  instances  the  sheaths  are  the  work  of  the  Rotifers 
inhabiting  them,  and  none  of  the  Sheath-building  Roti- 
fers are  free-swimmers.*  Most  of  the  free  swimmers, 
however,  may  become  temporarily  adherent  by  means  of 
their  foot  and  toes.  The  body  of  these  free-swimming 
forms  may  be  soft  and  flexible,  and  without  any  greater 
protection  than  is  afforded  by  the  skin,  or  it  may  be  en- 
closed within  a  hard,  shell-like  coating  called  a  carapace. 
The  bodies  of  all  the  sheath-building  Rotifers  are  with- 

*  Since  the  above  was  written  three  have  been  discovered  in  Eng- 
land. But  this  need  not  trouble  the  beginner. 


202  MICROSCOPY  FOR  BEGINNERS. 

out  a  carapace,  the  lorica  being  a  sufficient  protection. 
In  the  other  kinds  the  carapace  is  colorless  and  trans- 
parent as  a  glass  box,  all  the  creature's  organs  being 
plainly  visible  through  its  walls.  The  front  part  of  the 
body,  which  bears  the  cilia  or  the  ciliary  disks,  and  often 
the  long  tail-like  prolongation  of  the  posterior  part,  can 
be  drawn  within  the  carapace,  and  the  Eotifer  thus  shut 
in  and  protected  from  harm.  The  soft-bodied  forms 
have  a  similar  habit  of  drawing  in  the  two  ends,  taking 
advantage  of  the  hardened  skin.  This  is  one  of  the 
Rotifer's  characteristics. 

The  long  tail-like  part  at  the  posterior  end  of  the 
body  is  called  the  foot,  and  the  two  or  more  short  divis- 
ions at  the  free  end  of  the  foot  are,  of  course,  the  toes. 
The  true  tail  of  the  Rotifer  is  usually  a  small  affair, 
which  the  beginner  must  not  mistake  for  the  more  im- 
portant foot,  although  it  is  placed  on  the  foot,  some- 
times quite  near  the  body.  It  may  be  represented  by  a 
single  short  point,  it  may  be  in  two  parts  and  more  con- 
spicuous, or  it  may  be  entirely  absent.  The  uses  of  the 
foot  seem  to  be  to  act  as  a  rudder  to  guide  the  Rotifers 
when  swimming,  as  they  do  in  a  hurried,  headlong  way, 
and  also  to  anchor  them  when  they  desire  to  fish  for 
food.  The  toes  then  adhere  to  the  surface  of  the  slide 
or  of  any  other  object,  anchoring  and  holding  the  ani- 
mal against  the  propelling  power  of  the  ciliary  disks. 
In  some  of  the  group,  especially  in  the  commonest  of 
all — Rotifer  vulgaris — the  whole  foot  is  arranged  with 
joints  that  slide  on  each  other  like  the  joints  of  a  spy- 


ROTIFERS.  203 

glass.  In  this  and  similar  forms  the  Rotifer  can  not 
only  swim,  but  it  can  crawl  by  fixing  the  front  of  the 
body  against  the  slide,  drawing  in  the  telescopic  joints 
of  the  foot  and  clinging  with  the  toes ;  the  front  is  then 
loosened,  the  foot  extends  and  carries  the  whole  body 
forward  for  a  short  distance,  when  the  action  is  re- 
peated. A  Rotifer  can  do  this  with  surprising  rapidity, 
and  so  travel  over  considerable  distances  in  a  short  time. 
The  mouth  is  usually  placed  between  the  two  ciliary 
disks,  when  they  are  present,  near  the  centre  of  the 
frontal  portion  of  the  body,  or,  in  some  forms,  it  is 
placed  near  the  front,  but  on  the  lower  surface  of  the 
animal.  Those  with  the  mouth  in  the  last  -  mentioned 
position  usually  feed  by  gliding  along  with  the  front  of 
the  body  in  contact  with  the  plant,  tearing  and  biting 
off  small  particles  as  they  go.  These  may  be  called  the 
nibbling  Rotifers.  Following  the  mouth  there  is  often 
a  tubular  passage  leading  to  a  pair  of  wonderful  jaws 
inside  of  the  body,  which,  with  a  low-power  objective, 
can  be  seen  in  action  through  the  transparent  tissues  of 
the  Rotifer.  These  jaws  are  always  present  in  these 
creatures,  and  are  a  great  help  to  the  beginner,  for  as 
soon  as  he  observes  them  pounding  and  crunching  away 
inside  of  a  transparent,  legless,  microscopic  animal,  he 
may  be  sure  that  his  specimen  is  a  female  Rotifer.  The 
ciliary  disk  may  be  absent,  or  replaced  by  arms,  hairs,  or 
some  other  substitute,  but  if  these  internal  jaws  are 
present  the  specimen  is  a  Rotifer,  and  can  be  nothing 
else.  By  some  observers'these  curious  organs  are  called 
10 


204  MICROSCOPY  FOR  BEGINNERS. 

the  gizzard,  which  they  are  not.  The  best  word  to  ap- 
ply to  them  is  mastax. 

The  mastax  is  the  most  hard-working  part  of  the 
creature's  anatomy,  except,  perhaps,  the  cilia.  "When 
the  currents  produced  by  the  latter  bring  an  acceptable 
morsel  of  food  to  the  mouth,  it  is  passed  down  to  the 
mastax,  where  it  is  crushed  and  allowed  to  go  on  to  the 
stomach.  In  some  Rotifers  this  part  is  very  compli- 
cated. In  the  simpler  forms  it  consists  of  two  appar- 
ently semicircular  plates  surrounded  by  a  thick  en- 
velope of  powerful  muscle,  the  flattened  sides  acting 
against  each  other  and  crushing  the  food  between  them. 
The  surface  of  each  plate  very  often  bears  several  trans- 
verse parallel  ridges,  to  be  seen  with  a  high  power,  each 
ridge  projecting  a  short  distance  beyond  the  straight  in- 
ternal edge,  to  form  short  teeth.  These  ridges,  when 
the  mastax  is  closed,  are  received  in  the  depressions  be- 
tween those  on  the  opposite  plate,  thus  making  an  ef- 
fectual crushing  instrument.  In  other  forms  the  mastax 
consists  of  three  parts,  one  being  immovable,  and  used 
as  an  anvil  on  which  the  other  two  pound  the  food  as  it 
passes  by.  In  the  nibbling  Eotifers  the  entire  mastax 
is  protruded  through  the  mouth,  and  bites,  tears,  and 
nibbles  at  acceptable  food  masses. 

If  the  beginner  finds  it  difficult  to  make  out  the 
form  and  structure  of  the  mastax,  as  he  probably  will 
when  it  is  examined  in  action  within  the  body,  he 
may  succeed  by  killing  the  Rotifer  with  a  strong  so- 
lution of  caustic  potassa  allowed  to  run  under  the  cover- 


ROTIFERS.  205 

glass  —  a  small  drop  at  a  time.  This  will  dissolve 
the  soft  parts,  and  permit  the  hard,  insoluble  mastax 
to  float  out,  when  it  can  be  examined  with  a  high- 
power  objective. 

The  Rotifers  are  reproduced  by  eggs,  which  are  some- 
times hatched  within  the  parent's  body,  when  they  are 
said  to  be  ovo-viviparous.  This,  however,  is  not  com- 
mon. The  eggs  are  usually  semitransparent,  ovoid  bod- 
ies, very  often  to  be  seen  on  the  slide  among  other 
matters,  with  the  Rotifer  partially  developed,  and  the 
mastax  grinding  away  inside  of  the  unhatched  body 
where  it  cannot  possibly  have  anything  to  crush.  The 
only  parallel  to  this  of  which  I  know  is  Professor  Agas- 
siz's  statement  that  the  jaws  of  the  young  snapping-tur- 
tle  snap  while  the  creature  is  still  in  the  egg.  The  Ro- 
tifers may  drop  their  eggs  anywhere  and  leave  them  to 
the  care  of  Nature,  or  they  may  prudently  attach  them 
to  a  leaf  or  some  other  aquatic  object.  Very  often  they 
are  adherent  to  the  posterior  part  of  the  parent,  and  are 
carried  about  until  the  young  are  hatched.  In  those 
permanently  attached  Rotifers  that  form  a  soft  sheath 
this  is  a  common  occurrence,  and  several  eggs  may  at 
almost  any  time  be  seen  in  the  lower  part  of  the  lorica, 
or  fastened  to  the  animal's  foot.  In  such  instances, 
when  the  young  are  hatched  they  creep  up  between  the 
parent's  body  and  the  side  of  the  sheath  and  escape  at 
the  front.  They  swim  about  for  a  short  time,  and  then 
secrete  or  build  a  sheath  of  their  own,  which  they  never 
voluntarily  leave.  The  eggs  are  usually  smooth  ;  some- 


206  MICROSCOPY  FOR  BEGINNERS. 

times,  however,  they  are  covered  with  short  spines  or 
hairs. 

It  is  a  curious  fact  that  although  there  are  male  and 
female  Eotifers,  the  males  are  seldom  seen.  In  some 
species  they  have  never  been  found,  and  are  therefore 
entirely  unknown.  Those  that  have  been  discovered 
are  much  smaller  than  the  females  of  the  same  species. 
They  are  always  free-swimming,  and  are  without  a  mas- 
tax  and  alimentary  canal,  or  with  the  latter  so  imperfect 
that  it  is  useless.  Male  Rotifers,  therefore,  never  take 
food.  It  is  not  probable  that  the  beginner  will  meet 
with  them,  or  at  least  will  recognize  them  as  the 
males. 

This  group  of  animals  is  almost  as  common  and  abun- 
dant as  the  Infusoria,  and  they  are  found  in  similar 
places.  They  are  specially  fond  of  hiding  in  masses  of 
Ceratophyllum.  Indeed,  almost  any  pond  or  shallow 
body  of  still  water  may  be  examined  with  a  certainty 
of  finding  them.  They  have  even  been  sparingly  ob- 
tained from  the  moss  that  grows  between  the  bricks  in 
damp  pavements.  Some  species  develop  in  vegetable 
infusions,  but  as  a  rule  they  prefer  fresh  water.  The 
beginner  will,  of  course,  not  expect  that  all  the  genera 
and  species  will  be  included  in  this  little  book.  He  will 
obtain  very  many  whose  names  he  cannot  hope  to  learn. 
He  can,  however,  know  them  to  be  Rotifers  by  the  pres- 
ence of  the  mastax,  which  makes  them  one  of  the  most 
easily  recognizable  groups  of  microscopic  animals.  They 
form  an  interesting  class  of  creatures  for  microscopic 


ROTIFERS.  207 

study.  Very  few  of  our  American  forms  have  been 
investigated,  and  there  is  no  one  book  in  the  English, 
nor,  so  far  as  I  know,  in  any  other  language,  to  which 
the  beginner  can  be  directed  for  help.  The  American 
"  Wheel-bearers  "  form  a  large  field  which  ought  to  be 
cultivated.  There  is  room  for  many  discoveries,  and 
an  opportunity  to  greatly  add  to  the  world's  store  of 
scientific  information. 

In  using  the  following  Key,  the  beginner  must  re- 
member that  the  sheath  of  some  of  the  Rotifers  is  very 
often  colorless  and  rather  difficult  to  see  clearly,  un- 
less it  has  particles  of  dirt  or  other  matters  adherent 
to  it.  At  other  times  it  may  be  conspicuous.  The 
Key  refers  to  only  those  forms  included  in  this  book. 

Key  to  some  Genera  of  Rotifers. 

1.  In  a  gelatinous  or  other  kind  of  sheath  (a). 

2.  Not  in  a  sheath,  but  growing  in  attached  clusters.  (<#). 
#    Free-swimming  (e). 

«.  Clustered ;  sheath  soft,  gelatinous,  colorless.    La- 

cinuldria,  1. 
a.  Not  clustered ;  sheath  gelatinous  (5). 

a.  Not  clustered ;  sheath  not  gelatinous  (c). 

b.  With  five  long,  erect,  ciliated  arms  on  the  front 

border.     JStep/ianoceros,  2. 
£>.  With  five  clusters  of  many  long,  fine,  radiating 

hairs  on  the  front  border.     Floscularia,  3. 
5.  With    two    ciliary   disks ;    sheath    tubular,   often 

branched.     Actinurus,  4. 


208  MICROSCOPY  FOR  BEGINNERS. 

c.  Sheath  formed  of  rounded  brownish  pellets.   Meli- 
certa,  5.  , 

c.  Sheath  membranous,  brownish  or  colorless.    Lim- 

nias,  C. 

d.  Ciliary  disk  horse-shoe  shaped.     Megalotrocha,  7. 

e.  "With  carapace  (g). 

e.  Without  carapace ;  ciliary  disks  two  (/"). 
f.  With   ten    or    twelve    short,   scattered,  recurved 

spines ;  toes  three.     Philodina,  14. 
f.  Without  spines;  foot  with  telescopic  joints,  toes 

two.     Rotifer,  8. 

f.  Without  spines ;  foot  with  telescopic  joints,  toes 

three,  the  middle  one  longest.     Actinurus,  4. 

g.  Carapace  with  a  vizor  -  like  projection   in  front. 

Stephanops,  9. 
g.  Carapace  circular ;  foot  long,  cylindrical,  retractile. 

Pterodina,  10. 
g.  Carapace  vase  -  shaped ;  foot  long,  with  two  very 

long  toes.     Dinocharis,  11. 
g.  Carapace  with  six  long,  narrow,  movable  fins  on 

each  side.     Polydrthra,  12. 
g.  Carapace  with  several  tooth-like  spines  on  the  front 

border.    Brachionus,  13. 

1.  LACDTDLARIA. 

The  clusters  contain  numerous  individuals  secreting 
a  common,  soft,  colorless,  or  pale  yellowish  short  sheath 
without  any  special  shape ;  it  surrounds  only  the  poste- 
rior part  of  the  colony  and  can  serve  as  a  very  slight 


ROTIFERS.  209 

protection,  if  any.  The  Eotifers  are  somewhat  trumpet- 
shaped  when  extended,  and  to  a  certain  extent  resem- 
ble Megalotrocha  (Fig.  147).  The  ciliary  disk  is  single 
and  horseshoe  shaped.  It  is  closed  and  drawn  partly 
into  the  body  when  the  Rotifers  retire  into  their  apol~ 
ogy  for  a  sheath,  as  they  often  do,  the  whole  colony 
continually  waving  and  bobbing  and  bowing  as  the 
members  retire,  or  ascend  and  expand  themselves.  The 
sheaths  usually  form  a  little  mass  of  jelly-like  sub- 
stance, from  all  parts  of  which  the  Rotifers  project. 
The  colonies  are  commonly  adherent  to  Ceratophyllum 
or  Myriophyllmn. 

2.  STEPHANOCEROS  (Fig.  142). 

The  body  of  this  the  most  beautiful  of  all  the  Roti- 
fers is  somewhat  spindle-shaped.  It  ends  in  a  long,  flex- 
ible, tail-like  foot  which  is  attached  to  some  submerged 
object,  and  has  five  long,  slightly  curved  arms 
arranged  in  a  row  about  the  edge  of  the  front 
border.  These  arms  are  held  aloft  and  form 
a  most  effectual  trap  for  wandering  Infusoria, 
which  are  attracted  or  drawn  into  it  by  some 
means  not  easy  to  make  out.  The  front  of 
the  body  is  like  a  deep  open  funnel  leading 
down  to  the  mouth,  mastax,  and  stomach. 
The  ordinary  ciliary  disk  is  absent,  being  re- 
placed by  the  arms,  but  around  the  inside  border  of 
the  funnel -like  front  there  seem  to  be  many  fine 
cilia  which  may  produce  the  currents  in  the  water. 


210  MICROSCOPY  FOR  BEGINNERS. 

They  are  very  difficult  to  see  even  with  a  high -power 

objective. 

The  sheath  is  usually  colorless  and  transparent,  with 
considerable  firmness.  It  often  surrounds  the  body  up 
to  the  origin  of  the  arms. 

When  a  small  animal  once  enters  the  cage  formed  by 
the  arms  it  seldom  escapes,  but  is  gradually  driven 
down  into  the  funnel,  when  the  Rotifer  partially  closes 
the  front  opening,  and  with  a  very  perceptible  gulp 
swallows  and  passes  it  on  to  the  mastax. 

/Stephanoceros  does  not  seem  to  be  very  common. 
The  writer  has  found  it  sparingly  on  Myriophyllum  as 
late  as  the  middle  of  November. 

3.  FLOSCULARIA  (Fig.  143). 

The  front  of  the  body  is  here  also  like  an  open  fun- 
nel, the  narrow  part  leading  to  the  mastax.     The  ciliary 
disk  is  replaced  by  five  little  rounded  elevations  on  the 
front  margin,  each  bearing  a  thick  clus- 
ter of  long,  fine,  radiating  hairs,  which 
are  flexible,  and  movable  at  the  ani- 
mal's will,  but  which  never  vibrate  like 
cilia.  The  long  foot  is  attached  to  a  sub- 
merged object,  and  is  surrounded  by  a 
soft  and  transparent  sheath.  When  the 
Rotifer  retires  into  this  protective  cov- 
Fig.  143.          ering,  it  folds  the  wide  front  part  of  the 

Floscularia  orudta. 

body  together,  the  clusters  of  long  hairs 
seem  to  become  much  tangled  into  a  single  bunch,  and 


ROTIFERS.  211 

the  creature  slips  back  into  the  sheath.  When  she  comes 
out,  the  bunch  of  hairs  tremble  in  a  very  pretty  way, 
reminding  the  observer  of  the  quivering  appearance  of 
hot  air  often  seen  on  a  summer  day.  The  front  border 
opens,  the  clusters  of  hairs  are  spread  apart,  and  the 
Rotifer  is  ready  for  something  to  eat.  Any  little  ani- 
mal slipping  in  between  the  hairs  seldom  comes  out 
again.  The  Floscularia  gently  contracts  the  frontal 
opening  and  directs  the  victim  towards  the  mouth, 
where  it  is  gulped  down  as  in  Stephanoceros,  and  the 
mastax  finishes  it.  Several  eggs  are  often  seen  at- 
tached to  the  foot.  This  splendid  Eotifer  is  common, 
and  where  one  is  found  others  will  usually  be  near  by. 

4.  ACTINUKUS  (Fig.  144). 

When  a  bottle  of  pond  water  and  various  plants  is 
allowed  to  stand  for  a  while  undisturbed,  there  will  of 
ten  form  on  the  sides  very  delicate,  thread-like  objects, 
frequently  branching  and  otherwise  resem- 
bling brownish  Algse,  waving  and  trembling 
as  the  bottle  is  stirred.     They  are  so  soft 
that  they  can  hardly  be  removed  with  the 
dipping-tube  without  breaking  them.   They 
are  the  sheaths  of  a  Rotifer.     She  makes 
them  from  a  sticky  secretion  exuded  by  her 
body,  and  small  particles  of  any  matters  that 
may  be  floating  in  the  vicinity.    The  inside 
seems  to  be  smooth,  but  the  outside  is  rough  and  irreg- 
ular.   The  Rotifer  projects  from  the  open  end,  clinging 
10* 


212  MICROSCOPY  FOR  BEGINNERS. 

to  one  inside  wall  by  the  tips  of  her  toes,  and  as  the 
tube  lengthens  by  the  deposit  of  new  material  at  the 
top,  she  takes  a  step  forward  so  as  to  keep  her  expanded 
ciliary  disks  in  the  open  water.  If  the  student  will  al- 
low a  mixture  of  fine  indigo  and  water  to  run  under  the 
cover-glass,  he  will  see  the  formation  of  the  sheath.  A 
blue  ring  of  indigo  will  very  soon  appear  at  the  top  of 
the  soft  tube. 

In  appearance  the  Eotifer  resembles  Rotifer  vulgdms 
(Fig.  148),  and  when  out  of  the  tube,  which  she  can 
leave  at  will,  has  similar  actions.  There  are  two  ciliary 
disks,  and  usually  two  eye-spots.  The  foot  is  long,  and 
can  be  drawn  into  the  body  by  telescopic  joints.  It  has 
three  toes,  the  middle  one  being  the  longest.  The  eggs 
are  hatched  within  the  parent's  body.  The  Rotifers  oc- 
cupying the  branches  of  the  sheath  are  probably  all 
members  of  the  same  family — mother,  children,  and 
grandchildren — the  young  forming  the  branches. 

There  is  a  species  of  this  genus  which  does  not  form 
a  sheath.  It  may  be  known  by  its  resemblance  to  Ro- 
tifer vulgaris,  and  by  the  three  toes,  the  middle  one 
being  the  longest. 

5.  MELICERTA  (Fig.  145). 

The  sheath  of  Melicerta  resembles  that  of  no  other 
common  Rotifer.  It  is  built  of  pellets,  which  she  makes 
and  places  in  rows  around  her  body,  thus  erecting  a  red- 
dish or  yellowish-brown  lorica  that  cannot  be  mistaken. 
The  body  itself  is  colorless,  and  is  always  attached  by 


ROTIFERS.  213 

the  tip  of  the  long  foot  to  an  aquatic  object.  The  cil- 
iary disk  consists  of  four  parts  or  lobes  of  different 
shapes  and  sizes,  and  the  little  creature  also  has  a  very  pe- 
culiar and  rather  complicated  organ  for  making 
the  pellets.  The  whole  front  part  of  the  body 
can  be  folded  together  into  a  rounded  mass 
when  Melicerta  is  frightened  and  retires  to 
her  sheath.  "When  her  fright  is  over,  she 
slowly  protrudes  this  rounded  mass  from  the 
aperture,  gradually  spreads  it  open,  sets  the 
cilia  at  work,  and  proceeds  to  eat  and  build. 
The  last  she  seems  to  do  almost  continuously. 
As  her  body  grows,  her  house  must  be  enlarged  to  re- 
ceive it. 

The  ciliary  disk  of  Melicerta  will  repay  the  most  care- 
ful study.  And  careful  observation  will  be  needed  to 
learn  just  how  the  three  distinct  currents  that  she  makes 
in  the  water  are  produced.  One  current  brings  food 
particles  to  the  mouth,  where  she  selects  the  acceptable 
morsels  and  passes  them  on  to  the  mastax ;  a  second 
current  carries  away  the  fragments  for  which  she  has  no 
use ;  and  the  third  sets  in  towards  the  little  organ  that 
makes  the  pellets.  This  is  a  small  cavity  into  which 
the  building  material  is  poured,  and  where  it  is  turned 
about  rapidly  by  the  fine  cilia  which  line  it.  A  sticky 
secretion  is  exuded  that  causes  the  particles  to  adhere  to 
each  other,  and  the  revolving  motion  gives  the  pellet 
the  shape  of  a  Minie-bullet.  When  the  latter  is  formed 
to  the  Kotifer's  liking,  and  all  is  ready  for  the  final  act, 


214  MICROSCOPY  FOR  BEGINNERS. 

Melicerta  turns  herself  in  the  tube,  bends  her  body,  and 
deposits  the  pellet  on  the  top  row,  where  she  cements  it 
in  place  with  an  invisible  insoluble  cement.  The  whole 
is  done  so  quickly  that  the  first  time  the  observer  sees 
it  he  is  so  surprised  that  he  sees  nothing.  It  is  remark- 
able that,  as  a  rule,  she  forms  the  pellet  while  standing 
on  the  side  of  the  sheath  opposite  to  the  point  where 
she  means  to  place  it.  The  pellets  have  often  been  de- 
scribed as  round  balls,  but  the  student  will  see  that  they 
are  conical,  and  that  the  pointed  ends  are  on  the  out- 
side. Melicerta  is  quite  common  on  Ceratophyllum. 

6.  LIMNIAS  (Fig.  146). 

The  sheath  that  this  Rotifer  forms  is  a  rather  stiff, 
membranous,  nearly  cylindrical  tube,  somewhat  widest 
at  the  upper  part.  When  young  it  is  usually  colorless 
and  smooth,  but  it  changes  with  age,  becom- 
ing brown  or  blackish,  and  floating  particles 
roughen  it  by  adhering  to  the  outside.  The 
animal  living  within  it  is  colorless,  and  has  the 
ciliary  disk  divided  into  two  lobes,  which  she 
folds  together  when  frightened  and  forced  to 
retire  to  the  back  part  of  the  sheath  for  pro- 
tecti°n-  The  sheath  is  secreted  from  the  body 
of  the  Rotifer ;  it  is  not  built  of  particles 
picked  out  of  the  currents  from  the  ciliary  disks.  It  is 
common  on  the  leaflets  of  Ceratophyllum,  and  is  prob- 
ably named  Limnias  cemtopliylli  for  that  reason,  al- 
though it  is  found  almost  as  often  on  Myriophyllum. 


ROTIFERS.  215 

There  is  another  species  of  Limnias  also  quite  com- 
mon in  the  writer's  locality,  which  differs  from  Limnias 
ceratophylli  in  having  the  sheath  apparently  formed  of 
narrow  rings,  so  that  the  edges,  as  seen  under  the  mi- 
croscope, seem  finely  waved  or  scalloped.  By  this  it 
can  be  easily  distinguished  from  the  above.  It  is  named 
Limnias  annuldta. 

1.  MEQALOTBOCHA  (Fig.  147). 

The  clusters  formed  by  Megalotrocha  are  sometimes 
so  large  that  they  are  visible  to  the  naked  eye  as  whitish 
bodies  clinging  to  Myriophyllum,  which  it  seems  to  pre- 
fer. With  a  pocket-lens  the  individual  Roti- 
fers may  be  seen  rising  and  bobbing  as  they 
expand  or  contract,  but  a  low  power  of  the 
compound  microscope  is  needed  to  appreciate 
their  beauty.  The  expanded  body  is  rather 
trumpet  -  shaped,  very  soft  and  flexible,  and 
when  young  is  colorless.  As  it  grows  old  it 
becomes  slightly  yellowish.  The  eggs  are  FI&UT. 

Megalotrocha. 

often  to  be  noticed  adhering  to  the  lower 
part  of  the  parent.  "When  the  young  one  is  hatched 
it  either  remains  in  the  old  colony  or  it  leaves  and 
founds  ,a  new  cluster,  so  that  in  favorite  localities  col- 
onies of  almost  any  number  of  members  may  be  ob- 
tained. The  Eotifers  of  old  colonies  are  often  infested 
by  an  Infusorial  parasite,  which  runs  over  the  surface 
and  apparently  feeds  on  the  mucous  matters  secreted 
by  the  Rotifers'  skin.  It  is  called  Chilodon  megalo- 


216  MICROSCOPY  FOR  BEGINNERS. 

trochee,  and  somewhat  resembles  the  Chilodon  shown  in 
Fig.  128. 

8.  ROTIFER  VULGARIS  (Fig.  148). 

This  is  the  commonest  of  all  the  Rotifers.  The  body 
is  spindle-shaped,  tapering  to  both  ends  when  the  two 
ciliary  disks  are  unfolded.  The  foot  has  two  short  toes, 
and  can  be  drawn  into  the  body  by  its  telescopic 
joints.  Between  the  two  ciliary  lobes  is  a  cy- 
lindrical projection  ciliated  on  the  tip,  and  near- 
ly always  bearing  two  little  red  eye-spots  close 
together.  It  is  called  the  proboscis.  When 
hungry  the  Rotifer  clings  to  the  slide  by  her 
two  toes,  expands  the  ciliary  disks,  and  sends  a 
food-bearing  current  through  the  mouth  to  the 
mastax<  When  desirous  of  changing  her  place, 
she  may  either  loosen  her  hold  with  the  toes 
and  be  carried  through  the  water  by  the  action  of  the 
cilia,  or  she  may  fold  the  ciliary  lobes  together  and  go 
looping  about  by  clinging  with  the  tip  of  the  proboscis 
while  she  draws  up  the  foot,  when,  fastening  it  to  a  new 
point,  she  lets  go  with  her  proboscis,  extends  the  body, 
takes  a  new  hold  with  the  foot,  and  thus  moves  about 
quite  rapidly,  somewhat  after  the  manner  of  the  "  meas- 
uring-worms." 

9.  STEPHANOPS  (Fig.  149). 

There  are  several  species  of  these  pretty  little  Roti- 
fers, all  of  which  may  be  known  as  members  of  this 


ROTIFERS.  217 

genus  by  the  extension  of  the  front  of  the  carapace 
over  the  ciliary  disk,  like  the  visor  of  a  boy's  cap.  A 
not  uncommon  species  is  shown  by  Fig.  149,  in  side 
view,  so  as  to  exhibit  the  long,  movable  bristle  springing 
from  the  back,  and  the  curved  visor 
which,  in  the  figure,  looks  like  a  line 
above  the  frontal  cilia.  The  Rotifer 
is  one  of  the  nibblers.  The  mastax  is  protruded  from 
the  mouth,  which  is  near  the  front  of  the  lower  flat- 
tened surface,  and  bites  and  tears  the  food  it  meets 
with.  It  is  often  to  be  seen  gliding  over  aquatic  plants, 
nibbling  as  it  goes.  The  carapace  is  thin  and  quite 
flexible.  It  extends  over  the  sides  of  the  body,  so  as 
to  give  the  Eotifer  an  ovate  outline  when  seen  from 
above  or  below.  The  bristle  on  the  back  is  very  mov- 
able and  flexible. 

In  one  of  the  species  the  carapace  is  prolonged  at 
the  posterior  border  into  two  lateral  teeth.  In  another 
this  part  is  without  teeth,  and  the  dorsal  bristle  is  also 
absent,  as  it  is  in  all  the  known  American  species,  except 
the  one  shown  in  Fig.  149. 

10.    PTEBODfNA  (Fig.  150). 

The  carapace  is  almost  circular,  much  flattened,  and 
perfectly  transparent.  The  anterior  border  has  a  broad 
notch  with  rounded  margins,  over  which  extends  a  lip 
with  a  central  rounded  projection.  The  ciliary  disks 
are  two,  and  rather  widely  separated.  In  the  figure  they 
are  shown  retracted  into  the  body.  There  are  usually 


218 


MICROSCOPY  FOR  BEGINNERS. 


two  eye-spots.  The  foot  is  long,  tail-like,  very  flexible, 
and  apparently  formed  of  narrow  rings.  It 
can  be  withdrawn  entirely  into  the  carapace, 
and  the  Rotifer  seems  to  take  pleasure  in 
doing  so.  It  has  no  tail,  but  is  terminated 
by  a  small  sucker  bordered  by  a  circle  of 
tine  cilia.  The  Rotifer  is  often  seen  among 

Ceratophyllum  leaflets. 

11.  DINOCHARIS  (Fig.  151). 

The  transparent,  glassy  carapace  is  rather  squarely 
vase-shaped  and  somewhat  flattened.  It  gen- 
erally has  a  tooth-like  projection  on  each  side 
of  the  posterior  border.  The  Rotifer  can  al- 
ways be  recognized  by  its  two  very  long  toes, 
in  one  common  species  one  toe  being  very 
much  longer  than  the  other.  The  foot  is 
formed  of  two  joints  slightly  enlarged  at  the 
ends. 

12.  POLYARTHRA  (Fig.  152). 

The  form  of  the  carapace  is  somewhat  like  an  egg, 
with  both  ends  cut  squarely  off.  The  character,  how- 
ever, by  which  the  Rotifer  may  always  be 
known  is  the  presence  of  the  twelve  long, 
serrated  fins  which  project  backward  from 
the  front  part  of  the  upper  and  lower  sur- 
faces. They  are  arranged  in  clusters  of 
three  fins  each,  one  cluster  being  on  each 
side  below,  and  one  on  each  side  above.  By  them  the 


Fig.  151. 
Diu6charis. 


ROTIFERS.  219 

Rotifer  makes  long,  quick,  very  sudden  leaps,  often 
jumping  so  rapidly  that  it  can  hardly  be  seen ;  it  ap- 
pears to  spread  the  fins  and  disappear.  Occasionally  it 
turns  a  complete  somersault.  The  cilia  are  arranged  in 
a  row  along  the  front  border.  There  is  no  foot.  The 
mastax  is  pear-shaped  and  large,  but  its  structure  is  dif- 
ficult to  make  out.  The  Rotifer  has  only  one  eye, 
which  is  near  the  centre  of  the  upper  front  surface. 
The  little  creature  has  been  called  by  some  writers  the 
"  sword-bearer,"  and  is  said  to  be  quite  common  in  some 
localities,  but  I  have  never  been  fortunate  enough  to 
find  it. 

13.  BBACHIONUS  (Fig.  153). 

There  are  several  species  of  this  genus,  all  of  which 
may  be  known  by  the  presence  of  a  carapace  with  sev- 
eral tooth-like  projections  or  spines  at  the  front,  and 
often  also  at  the  rear,  by  the  two  ciliary  disks 
and  the  single  eye-spot.  The  species  whose 
empty  carapace  is  shown  in  Fig.  153  is  strict- 
ly American.  It  is  very  attractive  in  its  glass- 
like  transparency,  active  movements,  and  beau- 
tiful carapace.  It  was  discovered  by  Mr.  H. 
F.  Atwood,  of  Rochester,  and  named  Brach- 
ionus  conium  by  him.*  It  is  quite  common,  and  may 
be  easily  recognized  by  the  ten  long  teeth  or  spines 
on  the  front  border — the  central  one  on  the  upper  side 
or  back  being  largest,  and  bent  at  a  right  angle — and  by 

*  American  Monthly  Microscopical  Journal,  June,  1881. 


220  MICROSCOPY  FOR  BEGINNERS. 

the  four  posterior  ones.  The  foot  is  long  and  narrow, 
and  has  two  toes.  Eggs  are  occasionally  to  be  noticed 
attached  to  the  posterior  part  of  the  carapace. 

14.  PHILODINA  (Fig.  154). 

This  is  readily  distinguished  from  the  common  Roti- 
fer  (Rotifer  vulgaris)  by  the  spines  scattered  over  the 
back  and  sides  of  the  hardened  and  minutely  roughened 
body,  by  the  three  toes,  and  by  the  two  eyes 
being  some  distance  from  the  front  border, 
while  in  Rotifer  vulgaris  they  are  close  togeth- 
er on  the  proboscis.  The  species  referred  to  is 
shown  in  the  figure  with  the  body  partly  con- 
Fig.  164.  tracted,  the  ciliary  disks  and  foot  entirely  so. 
The  body  is  flexible,  yet  the  skin  is  hardened 
and  bears  the  conspicuous  recurved  spines,  two  of  which 
are  on  the  sides — one  on  each — and  pointing  forward. 
The  tail  is  divided  into  two  parts,  which  are  shown  in 
the  figure,  projecting  beyond  the  body.  The  Rotifer  is 
peculiar,  and  not  uncommon.  I  have  found  it  in  sum- 
mer, and  have  taken  it  from  under  the  ice  in  February. 


FRESH-WATER  TOLYZOA.  221 


CHAPTER  IX. 

FKESH-WATER    POLYZOA. 

THE  reader  now  approaches  a  group  of  microscopic 
animals  whose  beauty  is  so  exquisite,  so  delicate,  so  re- 
fined in  its  comeliness  and  grace,  that  no  description 
could  be  too  extravagant,  no  rhetoric  too  fervid  when 
applied  to  the  charming  little  creatures.  Yet  most  of 
this  fairness  seems  wasted  so  far  as  human  appreciation 
is  concerned,  for  how  few  among  the  millions  of  human 
beings  in  all  the  land  know,  or  care  to  know,  what 
the  Polyzoa  are,  or  how  they  look,  or  where  they  live, 
or  whether  they  live  at  all  ?  Nature  was  never  in  bet- 
ter mood  than  when  she  began  the  development  of  the 
Polyzoa,  so  she  fashioned  them  with  care,  and  placed 
them  most  abundantly  in  all  our  slow  streams  and  shal- 
low ponds,  where  they  live  and  die  and  melt  away  in 
the  shade  of  the  lily-leaves,  where  no  human  eye  sees 
their  loveliness  until  a  wondering  lover  of  Nature  spies 
them  and  is  happy. 

The  word  Polyzoa  is  formed  of  two  Greek  words 
meaning  "  many  animals,"  referring  to  their  habit  of 
living  in  colonies  which  sometimes  reach  an  immense 
size.  They  are,  with  but  one  exception,  always  at- 
tached to  some  submerged  object,  except  immediately 
after  leaving  the  egg,  when  the  young  animal  leads  a 


222  MICROSCOPY  FOR  BEGINNERS. 

short,  free  -  swimming  life.  "When  once  attached  they 
are  adherent  till  death.  The  animals  themselves  are 
small,  but  often  apparent  to  a  trained  eye ;  they  are  al- 
ways visible  under  a  good  pocket-lens.  The  colonies,  how- 
ever, of  all  the  fresh-water  forms  need  no  magnifying; 
some  of  them  are  very  conspicuous.  These  communi- 
ties are  formed  of  the  protective  coverings  or  sheaths 
secreted  by  the  animals.  Some  take  the  form  of  very 
narrow,  brownish  tubes,  adherent  to  the  lower  surface 
of  floating  chips,  boards,  waterlogged  sticks,  or  even 
occasionally  to  lily -leaves  or  the  submerged  stems  of 
grasses.  The  little  tubes  branch  like  miniature  trees, 
and  spread  over  the  surface  as  if  the  delicate  tree  had 
been  flattened  down  and  pressed  so  hard  that  it  could 
never  again  rise  up ;  or  they  may  be  attached  by  the 
base  only,  the  trunk  and  the  branches  then  floating 
and  waving  in  the  water.  The  animals  secreting  these 
tubes  live  in  them,  projecting  a  part  of  the  body  beyond 
the  orifice,  and  very  quickly  retreating  when  frightened. 
And  they  are  usually  very  timid,  retiring  into  the  tubu- 
lar home  at  a  slight  disturbance  of  the  water,  needing  a 
long  time  in  which  to  recover  and  again  look  out  at 
the  entrance  and  spread  their  beautiful  tentacles. 

In  other  forms  the  colony  is  surrounded  by  a  thick, 
rather  firm,  jelly-like  material,  from  which  the  animals 
protrude  themselves,  and  into  which  they  retreat.  These 
jelly  masses  are  usually  colorless  and  semitransparent, 
or  they  may  be  tinged  a  pale  red.  They  are  to  be  found 
in  the  purest  of  still  water,  adherent  to  sticks,  capping  a 


FRESH-WATER  POLYZOA.  223 

submerged  stump  with  a  cushion  of  living  jelly,  cling- 
ing like  crystalline  globules  to  any  projecting  rootlet 
or  water -soaked  object  beneath  the  surface,  even  to 
smooth  stones.  In  bulk  they  may  be  like  a  boy's  mar- 
ble, or  a  cart-wheel,  with  every  intermediate  size.  They 
vary  so  much  that  to  find  a  good  comparison  is  not 
easy,  and  it  is  only  right  to  say,  lest  some  lover  of  these 
lovely  creatures  should  be  envious,  that  a  colony  the 
size  of  a  cart-wheel  has,  in  the  writer's  locality,  been 
found  but  once,  the  foundation  of  this  remarkable 
growth  probably  being  the  rim  of  an  old  wheel. 

When  the  tubular  or  the  jelly-like  colonies  are  re- 
moved to  the  collecting-bottle,  they  appear  lifeless  and 
unattractive.  The  jelly  may  excite  wonder  by  its  size, 
or  curiosity  to  know  what  it  can  be,  yet  otherwise  it 
will  not  be  noticeable.  But  wait  a  while.  Place  the 
bottle  in  the  shade  and  wait  a  few  minutes ;  then 
with  a  pocket-lens  look  at  the  surface  of  the  jelly  or 
the  tips  of  the  branching  tubes.  Treat  them  with 
care;  move  them  gently.  The  little  creatures  are 
easily  frightened,  and  like  a  flash  leap  back  into  their 
protective  case.  Perhaps  while  you  gaze  at  the  reddish 
jelly  a  pink  little  projection  appears  within  the  field  of 
your  lens,  and  slowly  lengthens  and  broadens,  retreating 
and  reappearing  it  may  be  many  times,  but  finally,  after 
much  hesitation,  it  suddenly  seems  to  burst  into  bloom. 
A  narrow  body,  so  deeply  red  that  it  is  often  almost 
crimson,  lifts  above  the  jelly  a  crescentic  disk  orna- 
mented with  two  rows  of  long  tentacles  that  seem  as 


224:  MICROSCOPY  FOR  BEGINNERS. 

fine  as  hairs,  and  they  glisten  and  sparkle  like  lines  of 
crystal  as  they  wave  and  float  and  twist  the  delicate 
threads  beneath  your  wondering  gaze.  Then,  while  you 
scarcely  breathe,  for  fear  the  lovely  vision  will  fade, 
another  and  another  spreads  its  disk  and  waves  its  sil- 
very tentacles,  until  the  whole  surface  of  that  ugly  jelly 
mass  blooms  like  a  garden  in  Paradise — blooms  not  with 
motionless  perianths,  but  with  living  animals,  the  most 
exquisite  that  God  has  allowed  to  develop  in  our  sweet 
waters.  Perhaps  you  make  an  inarticulate  cry  to  your 
companion,  who  is  probably  wondering  why  you  are  so 
still  and  what  you  are  doing  on  the  ground  with  the 
lens  so  close  to  the  bottle,  and  as  he  too  gets  down  and 
brings  his  lens  to  bear,  maybe  he  jars  the  water,  and 
the  lovely  Polyzoa  flash  their  tentacles  together  and 
dart  backward  into  the  mass,  leaving  it  as  indescribably 
ugly  as  before.  If  he  brings  you  to  task,  tell  him  to 
wait  and  look.  And  while  he  looks  the  little  bodies 
again  slip  outward,  the  crescentic  disks  again  spread 
wide  open,  the  shining  tentacles  unfold  and  curl  and 
lash  the  water  until  once  more  the  ugly  jelly  mass  be- 
comes a  thing  of  indescribable  beauty.  This  is  Pecti- 
natella,  well  named  the  magnificent. 

The  jelly  is  formed  by  the  animals,  and  is  in  reality  a 
collection  of  protective  loricae,  the  huge  masses  often 
found  being  the  result  of  the  increase  in  the  numbers 
of  the  Polyzoa  inhabiting  them ;  or,  as  must  frequently 
occur  where  they  are  very  abundant,  of  the  union  of 
many  contiguous  growing  colonies.  A  single  animal 


FRESH-WATER  POLYZOA.  225 

begins  the  colony;  it  becomes  two  by  a  process  of  bud- 
ding, the  bud  finally  becoming  another  Polyzoon,  se- 
creting more  jelly,  budding  in  its  turn,  so  that  the  com- 
munity may  in  the  end  contain  numberless  members, 
and  the  mass  may  measure  several  feet  in  diameter. 
The  color  of  the  animals  is  usually  a  pale  red  or  flesh 
tint,  deepening  to  crimson  about  the  mouth,  which  is 
placed  near  the  centre  of  the  crescentic  or  horseshoe- 
shaped  disk  of  tentacles.  In  the  largest,  and  therefore 
the  oldest,  colonies  the  jelly  may  exhibit  many  scat- 
tered white  spots  composed  of  carbonate  of  lime. 

There  is  another  jelly-forming  colony  called  Crista- 
tella,  which  the  beginner  may  mistake  for  young  Pecti- 
natella.  It  is  to  be  distinguished  by  the  absence  of 
those  great  masses  which  characterize  Pectinatella,  by 
the  general  appearance  of  the  colony,  and  by  its  motion. 
A  community  of  Cristatella  is  usually  long  and  narrow, 
often  measuring  several  inches  in  length.  One  species 
is  about  eight  inches  long,  one-fourth  of  an  inch  wide, 
and  one-eighth  thick.  Young  colonies  are,  of  course, 
smaller,  and  are  rounded.  It  has  the  power  which  no 
other  fresh-water  Polyzoon  possesses  —  to  travel  from 
place  to  place.  It  moves  very  slowly,  a  colony  about 
an  inch  in  length  moving  an  inch  in  twenty-four  hours. 

All  the  fresh-water  Polyzoa,  of  which  there  are  sev- 
eral genera  and  species,  have  on  the  front  part  of  the 
body  a  disk  which  bears  the  tentacles.  It  is  named  the 
lophophore,  and  is,  in  some  forms,  horseshoe-shaped,  in 
others  nearly  circular.  The  tentacles  are  arranged  on  it 


226  MICROSCOPY  FOR  BEGINNERS. 

as  on  a  base,  usually  in  a  double  row.  The  word  is 
Greek,  and  means  "  wearing  a  crest." 

In  those  Polyzoa  which  secrete  hardened,  tubular,  tree- 
like sheaths  on  the  surface  of  submerged  objects,  the 
lophophore  is  protruded  from  the  orifice  in  the  end  of 
the  branch  much  as  in  Pectinatella,  and  there  is  only 
one  animal  to  each  limb  and  hollow  twig.  The  protru- 
sion and  expansion  of  the  lophophore  can  be  seen  with 
a  pocket-lens,  as  in  Fig.  156  (from  Professor  Alpheus  Hy- 
att's work  on  the  Polyzoa),  when  it  resembles  in  form 
that  of  Pectinatella.  Those  inhabiting  the  tubular 
sheaths  seem  much  more  timid  than  the  gelatinous 
forms,  retreating  on  slighter  provocation,  and  remain- 
ing longer  before  they  reappear  and  again  spread  the 
lophophore  and  tentacles.  They  are  quite  as  graceful 
and  attractive  —  perhaps  they  are  more  so,  since  they 
seem  more  delicate  and  less  able  to  protect  themselves. 

The  tentacles  are  finely  ciliated,  as  the  microscope 
will  show.  The  currents  produced  by  the  active  vibra- 
tions of  the  cilia  on  the  sixty  to  eighty  tentacles  of  Pec- 
tinatella, or  the  eighteen  to  twenty  in  other  members  of 
the  group,  are  quite  powerful,  and  setting  in  towards 
the  centre  of  the  lophophore,  they  sweep  the  entrapped 
food  to  the  mouth.  The  body  of  the  Polyzoon  is  a 
transparent,  membranous  sack,  with  the  lophophore  and 
the  mouth  at  the  free  end,  most  of  the  rest  being  im- 
mersed in  the  jelly  or  concealed  in  the  brown  opaque 
sheath.  The  mouth  has  on  one  border  a  short,  tongue- 
like  organ,  which  can  close  the  opening  and  prevent  the 


FRESH -WATER  POLYZOA.  227 

escape  of  the  food.  Extending  from  the  mouth  to  the 
stomach  is  the  food  passage  or  oesophagus,  the  stomach 
itself  being  a  widened  tube,  usually  conspicuous  on  ac- 
count of  its  contents  and  the  alternate  narrow,  reddish- 
brown  and  yellow  bands  traversing  it  lengthwise.  It  is 
suspended  in  the  hollow  body,  and  is  bathed  by  a  color- 
less fluid  which  fills  the  cavity  and  extends  also  into  the 
hollow  tentacles.  The  stomach  is  followed  by  the  tubu- 
lar intestine,  which  curves  forward,  and  generally  opens 
below  and  on  the  outside  of  the  lophophore.  The  ani- 
mals have  no  heart  and  no  blood,  unless  the  liquid  in 
the  space  between  the  outer  walls  of  the  stomach  and 
the  walls  of  the  body  can  be  said  to  be  blood. 

When  the  animal  is  frightened,  the  sides  of  the  lo- 
phophore close  together,  the  tentacles  collect  themselves 
into  a  bundle,  and  the  front  of  the  Polyzoon  is  drawn 
back  into  the  body,  and  a  muscle  around  the  border 
closes  that  opening.  The  jelly  of  Pectinatella  and  the 
hardened  tubes  of  the  other  forms  are,  therefore,  the 
protectors  of  the  body,  while  the  body  receives  and  en- 
closes the  lophophore  and  tentacles,  which  are  thus 
doubly  protected.  When  the  danger  is  past,  the  tips  of 
the  bundle  of  tentacles  are  very  cautiously  pushed  out 
into  the  water,  the  lophophore  follows,  and  if  the  creat- 
ure's confidence  is  restored,  the  crowns  are  spread  open 
in  all  their  indescribable  grace  and  beauty. 

The  favorite  food  consists  of  small  Algae  and  Infuso- 
ria, which  the  ciliary  currents  sweep  towards  the  mouth, 
the  tentacles  forming  a  cage  from  which  the  little  ani- 
11 


228  MICROSCOPY  FOR  BEGINNERS. 

mals  seldom  escape  unless  the  captor  is  willing.  And 
not  only  are  the  tentacles  used  to  capture  the  food,  but 
"  for  a  multitude  of  other  offices.  They  are  each  capa- 
ble of  independent  motion,  and  may  be  twisted  or 
turned  in  any  direction ;  bending  inward,  they  take  up 
and  discard  objectionable  matter,  or  push  down  into  the 
stomach  and  clear  the  oesophagus  of  food  too  small  to  be 
acted  on  by  the  parietal  muscles." 

To  examine  the  Polyzoa  under  the  microscope  de- 
mands a  very  deep  cell  to  hold  a  large  quantity  of  water 
and  to  prevent  the  cover-glass  from  pressing  on  the 
bodies.  It  is  often  better  to  place  the  microscope  in  an 
upright  position  and  omit  the  thin  cover.  In  this  ar- 
rangement the  water  trembles  easily,  and  not  only  inter- 
feres with  the  distinctness  of  the  image,  but  terrifies  the 
timid  creatures  on  the  slide.  Thte  observer  must,  there- 
fore, be  careful  not  to  touch  the  table,  and  to  make  his 
examination  in  a  quiet  room.  They  will  ask  a  little  at- 
tention and  some  gentle  treatment,  but  what  they  will 
show  with  the  help  of  a  one-inch  objective  will  amply 
repay  the  outlay  of  time  and  patience. 

The  following  Key  to  the  genera  will  help  the  stu- 
dent to  name  the  forms  he  may  find. 

Key  to  Genera  of  Fresh-water  Polyzoa. 

1.  In  a  jelly  mass  (a). 

2.  In  adherent,  branching  cylindrical  tubes  (J). 

3.  In  adherent,  branching  colonies  formed  of  tubular, 

club-shaped  cells  (G). 


FRESH-WATER  POLYZOA.  229 

4.  In  adherent,  pendent  stems  formed  of  urn  -  shaped 

cells  (d). 

a.  Jelly  mass   rounded,  adherent,  often  very  large. 
Pectinatella,  1. 

a.  Jelly  mass  long,  narrow,  slowly  travelling.     Cris- 

tatella,  2. 
ft.  Lophophore  horse-shoe  shaped.     Plumatella,  3. 

b.  Lophophore  circular.     Fredericella,  4. 

c.  Lophophore   circular,  tentacles  in  a  single  row. 

Paludicella,  5. 

d.  Lophophore  circular  or  oval,  tentacles  in  a  single 

row.      Urnatella,  6. 

1.  PECTINATELLA  MAGNIFICA  (Figs.  155, 155a). 

The  appearance  to  the  naked  eye  of  the  colorless 
jelly-like  substance  siwroimding  the  bodies,  and  of  the 
animals  themselves,  has  already  been  referred  to. 

Pectinatella  is  not  sensitive  to  sound,  but  a  jar  or 
shock  to  the  water  sends  the  an- 
imals into   their  contracted  state 
very  suddenly.     The  colonies  are 
numerous  throughout  the  summer 
and  until  October.    They  are  most 
frequently  found  in  the  shade,  al- 
though they  may  live  in  the  sun  if 
below  the  water.     Exposure  to  air    Fig.  iss—pectinattiia  mag- 
and  sunlight  together  is  speedily 
fatal.     Therefore  transfer  the  jelly  to  the  collecting- 
bottle  as  soon  as  possible,  otherwise  you  will  have,  on 


230  MICROSCOPY  FOR  BEGINNERS. 

your  return  home,  nothing  but  a  softening,  slimy  mass 
that  will  soon  force  you  to  throw  it  away.  If  suspended 
in  a  large  vessel  of  water  kept  very  fresh  by  frequent 
change, Pectinatella  will  live  for  some  time  in  captivity. 
In  Fig.  155  (after  Hyatt)  is  shown  a  small  colony  with 
the  lophophores  and  tentacles  expanded  and  enlarged,  as 
they  appear  with  a  good  pocket-lens.  The  absence  of 
color  and  motion,  however,  makes  a  great  difference  in 
their  beauty. 

In  old  colonies,  especially  late  in  the  season,  there  are 
often  to  be  seen  very  many  small,  rounded,  brown 
bodies,  which,  as  the  animals  die,  float  to  the  surface  of 
the  water.  These  are  the  winter  eggs  or  statoblasts. 
They  are  formed  within  the  body,  and  escape  only  when 
the  Polyzoon  dies  and  melts  away,  when  they  float  out 
and  remain  unchanged  until  the*warmth  of  spring  de- 
velops them.  Under  the  microscope  the  stat- 
oblasts  of  Pectinatella  are  seen  to  be  encircled 
by  a  row  of  double  hooks,  as  shown  in  Fig. 
155«-  l  liave  collected  them  late  in  the  fall, 
of  Pectu  an(j?  keeping  them  in  a  small  aquarium  in  a 
warm  room,  have  had  them  hatch  out  in  No- 
vember. The  young  fastened  themselves  to  the  sides 
of  the  glass  bowl,  where  they  appeared  like  delicate 
grains  of  translucent  pearl.  There  was  no  jelly  at  this 
early  stage,  and  each  little  Pectinatella  stood  alone,  con- 
sequently all  the  internal  organs  were  even  more  dis- 
tinctly visible  than  usual  through  their  hyaline  bodies. 
I  hoped  to  see  them  develop  into  colonies,  but  the  sur- 


FRESH-WATER  POLYZOA.  231 

roundings  were  not  quite  favorable,  perhaps  the  proper 
food  was  not  attainable,  so  they  died. 

2.  CRISTATELLA. 

The  form  and  movements  of  Cristatella  have  already 
been  referred  to  on  page  225.  The  young  colonies  are 
rounded,  and  are  found  in  the  same  localities  with  Pec- 
tinatella.  The  statoblasts  are  circular  and  have  two 
rows  of  double  hooks,  one  row  around  the  border,  the 
other  nearer  the  centre.  In  both,  the  hooks  are  not  sim- 
ple as  in  Pectinatella,  but  have  several  branches  at  the 
top  of  the  stern,  and  the  tips  are  forked. 

According  to  the  writer's  experience,  Cristatella  is  not 
common. 

3.  PLUMATELLA  (Fig.  156). 

The  tubes  containing  the  animals  may  be  attached 
only  at  the  base,  or  the  whole  colony  may  be  adherent 
to  the  submerged  surface  on  which  it  grows.  It  is  to 
be  found  in  shallow  water, 
usually  near  the  shore.  To 
see  the  lophophore  and  ex- 
panded tentacles,  if  the  col- 
ony is  small,  it  may  be  re- 
moved by  slicing  the  wood 
to  which  it  is  attached,  the 

Fig.  156.-Humatella. 

slice  to  be  placed  in  a  watch- 
glass  of  water  on  the  microscope  stage,  which  must,  of 
course,  be  in  a  horizontal  position.     The  mirror  may 
then  be  swung  above  the  stage,  and  Phimatella  viewed 


232  MICROSCOPY  FOR  BEGINNERS. 

by  reflected  light  as  an  opaque  object.  It  is  exquisitely 
beautiful  in  this  position,  as  is  Pectinatella  or  any  of 
the  Polyzoa ;  but  the  animals  are  very  timid.  To  see 
the  expanded  tentacles  will  therefore  demand  much 
time  and  patience.  Plumatella  is  almost  as  common  as 
Pectinatella.  A  board  or  log  that  has  been  floating 
undisturbed  in  the  pond  will,  during  the  summer,  be 
quite  sure  to  afford  a  rich  harvest  of  Plumatella  if  its 
under-surface  be  examined. 

4.  FBEDEBICELLA. 

The  colonies  of  this  Polyzoon  are  found  in  the 
shadiest  places  and  near  the  shores  of  shallow  ponds, 
growing  like  Plumatella,  and  often  in  company  with  it, 
on  the  lower  surfaces  of  floating  or  submerged  objects. 
The  whole  colony  may  be  adherent,  or  only  the  base,  the 
stem  and  branches  then  floating.  A  single  animal  in- 
habits each  hollow  branch,  and  resembles  Plumatella  in 
appearance  and  structure.  It  may  be  distinguished 
from  Plumatella,  however,  by  the  oval  or  nearly  circu- 
lar lophophore,  that  of  Plumatella  being  horseshoe- 
shaped.  The  colonies  are  usually  small,  covering  a  small 
space.  The  tentacles  are  never  more  than  twenty-four 
in  number.  The  statoblasts  are  more  or  less  circular, 
and  are  without  spines  or  hooks. 

5.  PALUDICELLA  (Fig.  157). 

These  colonies  may  always  be  known  from  all  other 
tube-making  Polyzoa  by  their  jointed  appearance,  each 


FRESH -WATER  POLYZOA.  233 

joint  or  cell  being  club-shaped.  The  colonies  are  irreg- 
ularly branched,  and  are  built  up  of  a  single  row  of  cells 
placed  end  to  end,  the 
narrow  end  or  the  handle 
of  the  club  being  attached 
to  the  broad  end  of  the 
cell  immediately  behind 
it.  The  opening  through 
which  the  animal  pro- 
trudes its  Circular  lo-  Fig.  W.-Palndicella. 

phophore  is  at  one  side 

of  the  broad  end  of  each  cell  near  the  top.  The  base 
alone  may  be  attached,  or  the  stem  may  be  adherent  and 
some  of  the  branches  free,  as  in  the  figure. 

6.  URNATELLA  (Fig.  158). 

The  form  and  appearance  of  this  Polyzoon  are  so 
characteristic  that  it  need  never  be  mistaken ;  but  while 
the  other  members  of  the  group  are  usually  rather  con- 
spicuous objects  to  the  eye  of  a  microscopist,  Urnatella, 
must  be  especially  searched  for.  The  colonies,  or  stem- 
like  growths  which  it  forms,  are  composed  of  urn-shaped 
cells  or  segments  united  end  to  end,  and  attached  by  a 
single  disk-like  enlargement  to  the  supporting  object 
from  which  they  hang  suspended.  The  lower  surface 
of  stones,  beneath  which  the  water  constantly  flows, 
seems  to  be  Urnatella's  favorite  haunt.  The  stem-like 
colonies  of  urns  are  usually  found  two  together  pendent 
from  the  same  disk  of  attachment,  and  appearing  some- 


234  MICROSCOPY  FOR  BEGINNERS. 

what  like  a  string  of  beads — this  being  due  chiefly  to 
the  alternate  bands  of  brownish-white  and  black  sur- 
rounding the  urns.  In  length  the  stems  vary  from  one- 
eighth  to  one -sixth  of  an  inch,  rarely  reaching  one- 
fourth.  To  be  seen  on  a  wet  stone  with  the  unaided 
vision,  therefore,  demands  a  trained  eye. 

The  cells  or  urns  are  joined  end  to  end,  the  enlarged 
central  portion  of  each  being  light-colored,  while  both 
the  narrowed  ends  are  dark  or  black.  A  single  colony 
is  seldom  formed  of  more  than  a  dozen  urns,  the  stems 
thus  built  up  being  either  quite  straight  or  somewhat 
curved,  or  even  on  occasion  loosely  coiled.  At  times 
the  stem  is  branched,  the  secondary  stem  originating 
near  the  point  of  attachment  of  one  cell  with  the  pre- 
ceding, but  soon  falling  off  or  voluntarily  breaking 
away.  On  each  side  of  every  segment  of  the  mature 
stems  is  a  small,  cup-shaped  projection,  the  two  appear- 
ing almost  like  handles  to  the  urns.  These  are  sup- 
posed to  be  the  remains  of  the  branches  or  of  those 
segments  which  have  fallen  away  and  gone  to  begin 
new  colonies  in  another  place.  Each  urn,  therefore,  has 
at  some  time  two  urns  attached  to  it,  one  on  each  side, 
and  occasionally  a  specimen  will  be  found  with  one  or 
more  branches  still  adherent. 

The  central  enlarged  portion  of  the  urns  is  translu- 
cent, light-colored,  and  often  with  many  transverse  wrin- 
kles and  transverse  brown  lines.  It  is.  also  brown  spot- 
ted, and  has  many  little  tubercles  of  the  same  color. 
The  necks  of  the  urns  where  they  are  joined  together 


FRESH-WATER  POLYZOA.  235 

to  form  the  stems,  are  opaque  and  black.  The  first  or 
foundation  segment  of  the  growth  is  larger  than  the 
others,  and  its  base  expands  into  a  broad  disk,  which 
adheres  to  the  stone  and  supports  the  entire  stem. 
Through  the  centre  of  the  whole  -collection  of  urns 
passes  a  cylindrical  cord,  whose  purpose  would  seem 
to  be  to  strengthen  the  fragile  pile  and  to  give  it 
the  great  flexibility  which  it  has. 

The  two  segments  near  the  free  end  of  the  stem  are 
smaller  than  the  others  and  rather 
different  in  shape.  They  are  also 
nearly  transparent  and  colorless. 
They  seem  to  be  urns  in  the 
process  of  growth,  while  those 
below  are  matured  and  hardened. 
It  is  only  the  terminal  segments 
that  contain  the  living  animal, 
the  urns  forming  the  stem  below 
them  being  filled  with  a  soft,  trans- 
lucent, granular  substance  packed 
into  the  cavity  around  the  central 
cord. 

The  animal  that  produces  this 
beautiful    series    of  brown   urns 

Fig.  153.— Urnat611a. 

lives  at  the  free  end  of  the  pile 

solitary  and  alone  with  the  exception  of  the  temporary 
companionship  of  those  short  branches  which  sprout  out 
near  it,  as  shown  in  Fig.  158.  It  is  these  short  growths 
that  are  supposed  to  drop  off  and  leave  the  cup-shaped 
11* 


236  MICROSCOPY  FOR  BEGINNERS. 

scars  on  eacli  side.  Barely  are  there  more  than  two  of 
these  projecting  scars  on  each  urn.  The  animal  itself, 
which  terminates  the  main  stem  and  its  branches,  when 
in  active  condition,  appears,  Dr.  Leidy,  its  discoverer, 
says,  as  a  bell-shaped  body  with  a  widely  expanded  oval 
or  nearly  circular  mouth,  directed  obliquely  to  one  side 
or  ventrally.  The  mouth  of  the  bell  is  bordered  by  a 
broad  waving  band  or  collar,  from  the  inside  of  which 
springs  a  circle  of  tentacles.  Of  these  there  are  usual- 
ly sixteen,  though  sometimes  from  twelve  to  fourteen. 
They  are  cylindrical,  and  reflected  from  the  mouth  of 
the  bell.  They  are  invested  with  an  epithelium  fur- 
nished with  moderately  long,  active  cilia.* 

Like  most  of  these  beautiful  creatures,  Urnatella  is 
very  timid  and  sensitive.  At  the  slightest  disturbance 
the  tentacles  are  folded  together  and  drawn  into  the 
mouth  of  the  bell,  which  closes  around  them,  and  the 
entire  stem  suddenly  bows  itself  down  to  the  ground,  or, 
when  long,  rolls  itself  into  a  loose  coil. 

No  eggs  nor  statoblasts  have  been  observed.  During 
the  winter  the  urns  do  not  seem  to  become  separated. 
"Perhaps,  as  reproductive  bodies,  after  the  polyp-bells 
perish,  they  remain  in  conjunction  securely  anchored 
through  the  first  of  the  series,  and  are  preserved  during 
the  cold  of  winter  until,  under  the  favorable  condition 
of  spring,  they  put  forth  buds  and  branches,  which,  by 

*  "Urnatella  gracilis  :  A  Fresh-water  Polyzoon."  By  Professor 
Joseph  Leidy.  Journal  of  the  Academy  of  Natural  Sciences  of  Phil- 
adelpldu,  vol.  ix. 


FRESH -WATER  POLYZOA.  237 

separation  and  settlement  elsewhere,  become  the  foun- 
dation of  new  colonies." 

Thus  far  I  have  not  been  fortunate  enough  to  find  a 
specimen  of  Urnatella,  although  it  is  probably  not  rare 
among  stones  in  running  water.  A  sight  of  its  beau- 
tiful and  curious  collection  of  urns  tipped  by  its  grace- 
ful bell  and  swaying  tentacles  is  worth  many  a  long 
tramp,  and  careful  scrutiny  of  many  a  wet  stone.  My 
account  of  this  Polyzoon,  because  of  my  want  of  ac- 
quaintanceship with  it,  is  gleaned  from  a  paper,  already 
referred  to,  by  Dr.  Leidy,  who  discovered  and  named  it 
Urnatella  grdcilis. 

And  those  who  desire  to  be  fully  informed  as  to  the 
anatomy  of  the  charming  creatures  which  form  the 
group  of  the  fresh- water  Polyzoa,  and  to  distinguish  the 
several  species,  are  referred  to  Professor  Alpheus  Hy- 
att's work  on  "  The  Polyzoa,"  published  by  the  Essex 
Institute,  Salem,  Mass.,  and  to  Professor  Joseph  Leidy's 
papers  on  the  subject  in  the  Journal  of  the  Academy 
of  Natural  Sciences  of  Philadelphia. 


238  MICROSCOPY  FOR  BEGINNERS. 


CHAPTER  X. 

ENTOMOSTKACA   AND   PHYLLOPODA. 

THE  reader  is  familiar  with  the  crayfish,  lobster,  and 
crab  as  members  of  that  great  group  of  animals  called 
the  Crustacea,  because  they  are  covered  by  a  hard,  shelly 
coating ;  but,  with  the  exception  of  the  crayfish,  he  may 
associate  them  all  with  salt  water,  while  in  reality  our 
fresh-water  ponds  are  densely  peopled  with  minute  crus- 
tacean creatures.  The  little  fresh -water  animals  are 
often  enclosed  in  a  bivalve  shell,  which  some  of  them 
have  the  power  to  open  and  shut ;  or  the  back  of  the 
body  may  be  simply  hardened,  but  without  a  distinct 
shell.  The  feet,  or  legs,  are  usually  numerous,  and 
very  hairy  or  bristly,  and  in  one  section  of  those  re- 
ferred to  in  this  chapter  are  flattened,  and  each  one 
bears  near  the  body  a  flattened  plate;  consequently, 
since  these  parts  are  somewhat  leaf-like,  the  animals 
have,  as  a  class,  been  called  the  leaf-footed  or  the  Phyl- 
lopoda,  which  is  putting  the  words  into  Greek.  Yery 
many  others,  to  be  found  much  more  abundantly  and 
frequently  than  the  Phyllopoda,  are  without  these  plates, 
although  the  feet  are  as  numerous  and,  in  some,  almost 
as  flat,  and  the  shells  or  the  shelly  back  as  well  marked. 
These  have  been,  by  naturalists,  grouped  together  under 
the  name  of  the  Entomostraca,  meaning  little  animals 


ENTOMOSTRACA  AND  PHYLLOPODA.       239 

in  a  shell,  but  the  translation  of  the  word  has  no  dis- 
tinctive signification,  since  members  of  both  groups 
have  shells. 

The  Entomostraca  are  more  abundant  in  fresh  water 
than  the  Phyllopoda,  and  are  remarkably  active.  They 
are  usually  visible  to  the  unaided  eye  as  little  specks, 
skipping,  flirting,  or  jerking  themselves  through  the 
water,  although  probably  few  will  measure  more  than 
one-tenth  of  an  inch  in  length.  Under  the  microscope 
some  are,  as  already  stated,  seen  to  be  enclosed  in  a 
bivalve  shell,  and  others  are  entirely  free  from  so  dis- 
tinct a  covering.  The  feet  are  arranged  in  pairs,  and 
may  be  very  numerous.  They  serve,  in  the  shell-bear- 
ing forms,  not  only  as  swimming  organs,  but  as  gills  or 
similar  contrivances  for  the  absorption  of  air  from  the 
water  for  the  aeration  of  the  little  animals'  blood.  This 
is  probably  one  reason  why  they  are  kept  in  such  inces- 
sant motion.  Even  when  the  shell  -  bearing  Entomos- 
traca come  to  rest,  to  feed,  or  for  some  other  purpose, 
certain  of  the  feet  keep  up  a  ceaseless  beating  of  the 
water,  as  can  be  readily  seen  through  their  transparent 
case. 

The  mouth  parts  are  complicated,  much  patience  and 
microscopical  skill  being  needed  to  investigate  and  un- 
derstand them.  On  each  side  of  the  head,  however,  and 
usually  near  the  mouth,  are  two  thread-like  but  jointed 
organs  called  the  antennae,  and  these  the  beginner  must 
recognize,  as  they  often  become  important  aids  in  learn- 
ing the  animal's  name.  They  vary  in  length,  one  on 


240  MICROSCOPY  FOR  BEGINNERS. 

each  side  often  being  quite  short  and  difficult  to  see 
distinctly,  while  the  other  two  are  usually  long  and  con- 
spicuous. They  are  all  formed  of  short  and  well- 
marked  joints,  the  number  varying  greatly  in  the  dif- 
ferent genera,  and  sometimes  in  different  species  of  the 
same  genus. 

One  or  more  black  or  dark  red  eye-spots  are  com- 
monly present.  In  some  the  eye  is  single,  and  in  the 
centre  of  the  forehead.  It  may  also  be  slightly  movable 
at  the  will  of  its  possessor.  The  young  animal,  as  not 
rarely  happens,  may  have  two  distinct  eyes,  which,  as  it 
grows  older,  become  joined  into  one  and  covered  by  the 
shell. 

The  heart  is  very  frequently  visible,  especially  in  the 
shell-bearing  forms,  being  there  placed  at  the  back  of 
the  body  and  near  the  head.  It  beats  rapidly,  and  ap- 
parently sends  the  colorless  blood  quickly  through  the 
system. 

They  all  increase  and  multiply  through  the  formation 
of  eggs,  which  may  remain  within  the  shell  and  there 
be  hatched,  or  they  may  be  attached  to  the  parents'  body 
in  external  clusters.  In  the  shell-bearing  forms  they 
are  passed  into  a  brood  cavity  at  the  back  between  the 
body  and  the  shell,  where  they  are  kept  until  the  young 
are  hatched,  when  the  latter  make  their  escape  into  the 
water,  and  care  for  themselves.  In  those  without  shells 
the  eggs  are  passed  out  of  the  body  into  one  or  two 
small,  pear-shaped  sacks  called  external  ovaries,  where 
they  remain  until  hatched.  In  these  cases,  however,  the 


ENTOMOSTRACA  AND  PHYLLOPODA.       241 

egg  masses  are  carried  about  by  the  parent,  and  are  con- 
spicuous objects.  It  is  a  common  occurrence  to  find 
the  little  animals  apparently  loaded  with  the  burden  of 
eggs,  and  not  uncommon  to  see  the  young  escape.  The 
"  common  Cyclops"  is  an  instance.  No  member  of  the 
Entomostraca  is  so  frequently  seen  and  so  abundant  as 
the  Cyclops,  and  hardly  any  other  affords  so  good  an 
example  of  this  method  of  depositing  and  caring  for 
the  eggs  in  external  ovaries,  Cyclops  having  two  of  the 
latter,  while  some  other  almost  equally  common  forms 
have  but  one.  The  external  ovaries  are  usually  long, 
pear-shaped  bodies  attached  to  the  rear  of  the  animal, 
near  where  it  diminishes  to  form  its  tail -like  portion. 
The  eggs  are  round,  unless  they  are  made  polygonal  by 
pressure,  almost  black,  and  entirely  opaque.  In  Cantho- 
camptus  there  is  but  one  external  ovary.  Both  kinds 
are  shown  in  Figs.  166  and  167. 

The  young,  when  first  hatched,  bear  so  slight  a  re- 
semblance to  the  parent  that  some  of  them  have  been 
described  and  named  as  entirely  different  animals ;  and 
it  was  not  until  they  were  seen  leaving  the  egg  while 
still  attached,  or  in  the  external  ovary,  that  their  true 
character  was  discovered.  This  is  especially  true  of 
Cyclops.  The  young  animal  is  shown  in  Figure  1670. 
It  changes  its  skin  several  times  before  it  begins  to  re- 
semble its  mother,  a  similar  peculiarity  being  noticeable 
in  many  of  the  Entomostraca. 

These  little  crustaceans  are  found  in  almost  every 
body  of  still  water.  Some  prefer  the  surface,  where,  on 


242  MICROSCOPY  FOR  BEGINNERS. 

a  sunshiny  day,  they  are  occasionally  seen  in  immense 
numbers,  sinking  when  a  cloud  shades  them,  and  rising 
again  to  the  sunlight.  Others  are  to  be  taken  only  in 
deep  water,  while  still  others  can  be  obtained  only  at 
night.  Very  many,  however,  are  collected  in  every 
gathering  of  aquatic  plants.  They  abound  at  all  sea- 
sons of  the  year,  even  in  midwinter.  Their  movements 
are  rapid  and  characteristic.  An  Entomostracan  can  be 
readily  recognized  as  such  by  the  unaided  sight,  on  ac- 
count of  the  peculiar  leaping,  or  short,  jerking  motions 
with  which  it  travels  through  the  water. 

They  are  not  only  interesting  little  creatures  to  the 
microscopist,  but  they  are  extremely  useful  as  well. 
They  play  a  very  important  part  in  the  food  supply  of 
fishes,  forming  the  chief  article  of  diet  of  some  of  our 
best  fresh- water  fishes.  And  they  are  almost  as  impor- 
tant as  scavengers.  Their  favorite  food  is  dead  and 
decaying  Algae  and  animal  niatter,  which,  if  allowed  to 
remain  in  the  great  abundance  in  which  it  exists,  our 
ponds  ancl  slow  streams  would  before  long  become  pu- 
trid and  unbearable.  But  these  numerous  little  creat- 
ures, by  eating  this  refuse  matter,  transform  it  into  an 
innocent  and  innocuous  material,  and  confer  a  benefit 
both  on  themselves  and  us.  Mr.  C.  L.  Herrick,  writing 
on  this  subject,  says,  "  Their  importance  depends  large- 
ly on  their  minute  size  and  unparalleled  numbers.  The 
majority  of  non-carnivorous  crustaceans  are  so  consti- 
tuted that  their  diet  is  nearly  confined  to  such  floating 
particles  of  matter  as  are  present  in  the  water  in  a  state 


ENTOMOSTBACA  AND  PHYLLOPODA.       243 

of  more  or  less  fine  comminution ;  for,  nearly  without 
prehensile  organs,  these  animals,  by  means  of  a  valvular 
or,  at  most,  ladle-like  labrum,  dip  from  the  current  of 
water  kept  flowing  by  the  constant  motion  of  the  bran- 
chial feet,  such  fragments  as  the  snail  and  scavenger- 
fish  have  disdained :  bits  of  decaying  Algae,  or  the 
broken  fragments  of  a  disintegrated  mosquito,  all  alike 
acceptable  and  unhesitatingly  assimilated.  The  amount 
of  such  material  that  they  will  dispose  of  in  a  short  period 
of  time  is  truly  astonishing." 

When  the  shallow  ponds  are  dried  by  the  summer 
heat,  the  Entomostracans  bury  themselves  in  the  mud, 
and  there  remain  quiescent,  but  alive,  so  long  as  any 
moisture  is  present.  When  the  mud  is  completely 
dried  they  die,  but  the  eggs  have  the  ability  to  endure 
heat  and  dryness  without  injury,  and  to  develop  and 
mature  as  the  pools  again  become  filled  by  the  rain,  or 
by  the  melting  snow  of  early  spring. 

The  Phyllopoda  may  also  often  be  recognized  without 
a  microscopical  examination,  by  their  large  size  and  al- 
most universal  habit  of  swimming  on  the  back.  Bran- 
ckipus,  sometimes  called  the  fairy  shrimp,  and  Artemia, 
or  the  brine  shrimp,  are  nearly  an  inch  in  length. 

As  in  the  Entomostraca,  their  bodies  may  be  incased 
in  a  bivalve  shell  or  not.  The  broad,  flattened  feet  are 
numerous,  but  the  branchial  or  breathing-plates  already 
referred  to  may  be  small  and  inconspicuous,  and  there- 
fore difficult  to  be  observed  by  the  beginner.  They  are 
especially  well-marked  in  Artemia  (Fig.  169),  and  in 


244  MICROSCOPY  FOR  BEGINNERS. 

Brancliipus  (Fig.  170).  Eyes  are  usually  present,  and 
large.  In  some  forms  they  are  elevated  on  stalks,  thus 
reminding  the  observer  of  the  stalked  eyes  of  lobsters. 

The  eggs  of  the  bivalve  Phyllopoda  are  kept  within 
a  brood  cavity,  somewhat  as  in  similarly  incased  Ento- 
mostraca,  while  in  the  shell-less  forms  they  are  carried 
about  in  a  bottle-shaped  sack  at  the  end  of  the  body, 
near  the  origin  of  the  long,  narrow,  tail-like  portion.  In 
both  kinds  the  young  bear  scarcely  the  remotest  resem- 
blance to  the  adults. 

In  the  fresh  and  brackish  waters  of  the  eastern  part 
of  the  country  there  are  but  few  genera  of  the  Phyl- 
lopoda represented,  and  none  have  yet  been  found  in  the 
ocean ;  while  on  the  western  plains  and  among  the 
Kocky  Mountains  they  abound.  These  latter  forms  are, 
however,  not  included  in  those  referred  to  in  the  fol- 
lowing list. 

All  these  little  crustaceans  should  be  examined  in  a 
deep  cell,  to  prevent  the  weight  of  the  cover-glass  from 
crushing  their  bodies.  The  shells  and  the  shelly  coat- 
ing give  them  the  appearance  of  hardness,  but  they  are 
delicate  and  easily  injured.  The  large  Phyllopoda  will 
need  an  especially  deep  and  extensive  cell. 

The  following  Key  will  lead  to  the  common  genera 
of  both  divisions  of  these  attractive  animals.  The  only 
trouble  the  beginner  may  meet  with  in  using  at  will 
probably  be  in  determining  whether  the  specimen  is  a 
Phyllopod  or  an  Entomostracan ;  but  as  the  former  are 
large,  and  swim  on  the  back,  they  may  usually  be  deter- 


ESTOMOSTRACA  AND  PHYLLOPODA.       245 

mined  by  these  appearances,  and  the  name  learned  by 
the  Key,  in  connection  with  a  pocket-lens.  The  two 
Entomostracans,  Diaptomus,  and  Canthocamptus,  are 
separated  in  the  Key  by  the  number  of  the  joints  in 
their  long  antennae.  This  seems  to  be  a  very  minute 
character  to  use  in  so  artificial  a  table,  but  it  need  not 
be  an  annoyance  to  the  beginner,  since  the  antennae  of 
these  two  common  little  crustaceans  differ  so  conspicu- 
ously in  size  and  length  that  the  joints  need  not  be 
actually  counted ;  a  glance  will  show  which  is  Cantho- 
camptus,  with  its  short  and  rather  inconspicuous  an- 
tennae. 

The  beak  referred  to  is  the  front  part  of  the  shell 
extended  in  a  long,  usually  curved  and  pointed  prolon- 
gation, containing  the  eye  and  portions  of  the  animal's 
head. 

Key  to  Genera  of  Entomdstraca  and  Phyllopoda, 

1.  Legs  with  flat  plates  near  the  body ;  animal  swim- 

ming on  the  back  (A). 

2.  Legs  without  flat  plates  (a). 

a.  Body  enclosed  in  a  bivalve  shell  (b). 

a.  Body  not  enclosed  in  a  shell  (g). 

I.  Shell  with  a  sharp  posterior  spine  or  a  tooth  on 
or  near  the  upper  posterior  angle  (c). 

b.  Shell  without  a  posterior  spine,  or  with  one  to  four 

small  teeth  on  the  lower  posterior  angle  (d). 

c.  Smooth ;  spine  on  the  upper   angle,  or  near  the 

middle  of  the  border.     Ddphnia,  1. 


246  MICROSCOPY  FOR  BEGINNERS. 

c.  Smooth,  brown ;  spine  on  the  lower  angle.     Sca- 

pholeberis,  2. 
c.  Reticulated;  spine  on  the  lower  angle;  antennae 

large,  cylindrical.     Bosmina,  3. 

c.  Reticulated  ;  spine  or  tooth  on  the  upper  angle ;  an- 

tennae long,  witli  two  branches.    Ceriodaphnia,  4. 

d.  Beaked  in  front  (e). 

d.  Not  beaked,  oval,  both  ends  rounded ;  smooth  or 

hairy.     Cypris,  5. 

e.  Posterior  border  with   one  to   four  small   teeth. 

Camptocercus,  6. 

e.  Posterior  border  without  teeth  (f). 

f.  Shell  nearly  spherical ;  posterior  border  truncate. 

Chydorus,  7. 

f.  Shell  not  spherical ;  posterior  border  convex ;  an- 
tennas small.     Alonopsis,  8. 

f.  Shell  not  spherical;    posterior  border  truncate; 

antennae  large,  long,  and  branched.     Sida,  9. 

g.  Body  long  and  narrow ;  antennae  long,  twenty-five 

jointed.     Didptomus,  10. 
g.  Body  long  and  narrow ;  antennae  short,  four  to  ten 

jointed.     Canthocamptus,  11. 
g.  Body  racket  (battledoor)  shaped,  with  two  external 

ovaries.     Cyclops,  12. 
h.  Body  enclosed  in  a  bivalve  shell  (£). 
A.  Body  not  enclosed  in  a  shell  (/). 
i.  Shell  nearly  spherical,  smooth.     Limnetis,  13. 
*'.  Shell  oval  or  oblong,  flattened,  amber-colored,  with 

longitudinal  lines.     Estheria,  14. 


ENTOMOSTRACA  AND  PHYLLOPODA.  247 

j.  In  brine  pools  and  salt  lakes  ;  eyes  black,  on  stalks. 
Artemia,  15. 

j.  In  fresh  water ;  males  with  large  frontal  append- 
ages ;  females  without  frontal  appendages,  but 
with  an  external,  posterior,  broad,  short,  and  bot- 
tle-shaped egg-sack  (&). 

k.  Frontal  appendages  much  twisted  and  coiled ;  body 
slender.  Chirocephalus,  16. 

k.  Frontal  appendages  not  twisted  nor  coiled ;  body 
stout,  granchipus,  17. 

ENTOMOSTRACA. 
1.  DAPHNIA  (Fig.  159). 

There  are  several  species  of  Ddphnia,  all  of  which 
may  be  known  by  the  presence  on  the  posterior  border 
of  a  sharp  spine,  which  is  never 
on  the  lower  angle.  It  varies  in 
length  in  the  different  species, 
sometimes  being  nearly  as  long  as 
the  shell,  and  extending  oblique- 
ly upward.  It  also  varies  in  length 
and  in  position  on  the  same  indi- 
vidual, being  longest  in  the  young, 
and  becoming  quite  short  with 
age.  In  the  species  figured  (Ddph- 
nia  pulex)  it  is  usually  on  the 
upper  angle,  but  not  rarely  as  shown  in  the  cut.  In 
very  old  specimens  it  may  be  entirely  absent,  but  it  is 


248  MICROSCOPY  FOR  BEGINNERS. 

always  present  at  some  time  of  the  animal's  life.  The 
shell  is  oval  and  slightly  flattened.  The  antennae  are 
prominent,  and  are  usually  divided  into  two  parts  at 
the  free  end,  each  division  bearing  several  feathery 
bristles.  The  feet  are  flattened,  and  generally  in  rapid 
motion,  so  as  to  bring  food  to  the  mouth,  and  oxygen 
to  the  blood.  The  heart  is  noticeable  as  a  small  color- 
less organ  under  the  shell  of  the  back  near  the  head. 
It  pulsates  rapidly.  The  eye  is  large  and  conspicuous. 
The  eggs  are  placed  in  a  brood  cavity,  as  shown  in  the 
figure,  and  there  hatched,  the  young  being  very  different 
in  appearance  from  the  parent.  Daphnia  is  common 
in  the  spring. 

2.    SCAPHOLEBEUIS. 

The  shell  is  somewhat  beaked  and  usually  dark  brown. 
The  surface  may  be  indistinctly  reticulated  or  entirely 
smooth.  From  jBosmina,  for  which  the  beginner  may 
be  inclined  to  mistake  it,  the  absence  of  the  curved, 
cylindrical  antennae  common  to  that  species  will  distin- 
guish it.  The  posterior  spines  are  short.  The  eye  is 
large  and  conspicuous.  The  egg  is  carried  in  the 
brood  cavity.  It  is  said  that  but  one  egg  is  present  at 
a  time.  This  Entomostracan  is  common. 

3.  BOSMIKA  (Fig.  160). 

The  student  will  not  have  any  trouble  to  recognize 
£6smina,  on  account  of  the  long,  large,  cylindrical  an- 
tennae, each  one  curving  downward  from  the  side  of 


ENTOHOSTRACA  AND  PHYLLOPODA.       249 

the  head  like  the  trunk  of  a  microscopic  elephant.    The 

shell  is  oval,  colorless,  and  the  posterior  border  has  a 

spine  at  its  lower  angle,  never  at  any 

other  point.    The  net-work  of  lines  on 

the  surface  may  extend  over  the  entire 

shell  or  be  restricted  to  some  one  part. 

The  eye  is  large.    The  eggs  are  hatched 

in  a  brood  cavity  on  the  back  beneath  the  shell.     The 

heart  is  visible  near  the  centre  of  the  back.     Bosmina 

is  not  so  common  as  Daphnia. 

4.  CEKIODAPHNIA. 

The  shell  is  oval,  oblong,  or  somewhat  four-sided,  and 
always  beautifully,  if  coarsely  and  conspicuously,  reticu- 
lated, the  meshes  being  hexagonal  and  comparatively 
large.  The  head  is  separated  from  the  body  by  a  de- 
pression in  the  shell,  and  just  behind  the  rather  small 
eye -like  spot  it  has  a  slight  elevation.  The  eye  is 
usually  near  the  rounded  lower  margin  or  tip  of  the 
beak-like  head.  The  antennae  resemble  those  of  Daph- 
nia, being  long,  and  divided  into  two  three  -  jointed 
branches  of  equal  length.  The  angle  or  tooth  on  the 
upper  corner  of  the  posterior  border  is  usually  sharp 
and  conspicuous. 

This  Entomostracan  is  abundant  in  the  writer's  lo- 
cality. It  is  visible  to  the  naked  eye,  being  about  one 
twenty -fifth  of  an  inch  long.  In  the  aquarium  its 
movements  are  almost  distinctive.  It  seems  to  prefer 
the  centre  of  the  vessel,  where  it  darts  upward  for  a 


250  MICROSCOPY  FOR  BEGINNERS. 

short  distance  with  a  jerk,  only  to  allow  itself  to  float 
back  to  the  starting-point.  A  glass  jar  well  stocked 
with  these  pretty  creatures  leaping  up  and  down  ir- 
regularly and  incessantly  is  an  interesting  sight.  Un- 
der the  one-inch  objective  the  little  animal  is  more  than 
interesting. 

5.  CYPRIS  (Fig.  161). 

The  shell  entirely  surrounds  the  animal,  so  that  the 
little  creature,  when  danger  threatens,  shuts  itself  in  as 
completely  as  a  clam  or  a  mussel,  and  allows  itself  to  fall 
to  the  bottom.  The  form  varies  from  an  oval  to  a  kid- 
ney shape,  according  to  the  species,  and  the  color  may 
be  green  or  brown,  or  whitish  and 
marked  with  several  dusky  bands.  It 
may  be  smooth,  or  entirely  covered 

°r 


.  IClCypris 

ders  may  be  fringed.  The  shell  is 
never  opened  wide,  but  the  legs  and  feathery  antennae 
project  from  a  narrow  cleft  between  the  valves,  the  lit- 
tle animal  swimming  rapidly  by  their  aid,  or  creeping 
about  the  slide  or  over  the  aquatic  vegetation.  Cypris 
is  reproduced  by  eggs,  but  "  the  mass  of  eggs,  including 
about  twenty-four,  is  attached  by  the  female  to  water- 
plants  with  the  aid  of  a  glutinous  secretion,  an  opera- 
tion which  lasts  about  twelve  hours." 

6.  CAMPTOCERCTJS  (Fig.  162). 

The  shell  is  elongated,  somewhat  quadrangular,  trans- 
parent, and  marked  by  lines   traversing   the    surface 


ENTOMOSTRACA  AND  PHYLLOPODA.  251 

lengthwise.     The  beak  is   blunt,  and  usually  curved 

downward,  or  it  may  extend  slightly  away  from  the 

body.     The  head  is   strongly  arched. 

The  teeth  on  the  posterior  border  (not 

shown   in   the  figure)   are  small,  and 

vary  from  one  to  four.     The   eye  is 

small.      The    eggs    are    carried  in    a 

brood  cavity.     The  animal  occurs  chiefly  in  lakes  and 

large  ponds. 

7.  CHYDORUS  (Fig.  163). 
The  surface  of  this  nearly  spherical  shell  is  usually 

reticulated.     The  beak  is  long,  curved,  and  pointed, 

being  sharp  in  the  female.  The  posterior  border  is 
truncate  in  young  specimens,  becoming 
more  rounded  in  the  old.  The  eye  is 
present  and  single.  The  eggs  are  hatched 
in  the  brood  cavity.  The  animal  occurs 

Fig.  163.-Chydoms.    abundantly  yerj  ear]y  in  the  gprmg)  usu. 

ally  near  the  bottom,  living  chiefly  on  vegetable  mat-, 
ters.  The  motion  is  rolling  and  somewhat  unsteady, 
and  uncertain  in  appearance. 

8.  ALONOPSIS  (Fig.  164). 

The  lower  or  free  edge  of  the  shell  is  fringed  with 
bristles,  which  are  longest  in  front. 
The  beak  is  long,  pointed,  and  separat- 
ed by  some  distance  from  the  body  of 
the  shell.  Eye  large.  One  of  the  feet 
(the  third)  has  a  long  spine  fringed  with  "pig.  icL-Aionopsis. 
12 


252  MICROSCOPY  FOR  BEGINNERS. 

short  hairs  on  the  edges,  and  often  reaching  to  the  pos- 
terior margin  of  the  shell.  The  surface  is  usually 
marked  by  a  few  conspicuous  diagonal  lines.  The  ani- 
mal's movements  are  slow. 

9.  SIDA. 

The  shell  is  long  and  narrow,  with  the  head  separated 
from  the  body  by  a  depression.  The  posterior  margin 
is  nearly  straight,  and  has  no  spine  or  tooth.  The 
antennae  are  large,  and  somewhat  resemble  those  of 
Daphnia,  although  in  Sida  they  are  rather  stouter,  and 
are  divided  into  two  unequal  branches.  There  is  but 
one  species  —  Sida  crystallma.  It  is  quite  common  in 
some  localities. 

10.  DIAPTOMUS  (Fig.  165). 

Diaptomus  may  be  recognized  by  the  very  long  an- 
tennse,  which  are  often  as  long  as  the  body.  The  latter, 
including  the  head,  is  formed  of  six  joints,  and  the  pos- 
terior narrower  part  or  abdomen  of  five,  although  in 
the  female  two  of  the  latter 
may  be  united,  thus  giving 
it  a  three-jointed  appearance. 
The  animal  is  among  the 
largest  of  the  Entomostraca, 

Fig.  1C5 — Di&ptomus. 

often  measuring  one-tenth  of 

an  inch  in  length.  The  color  is  often  brilliant,  varying 
in  the  different  species,  and  even  in  the  different  parts 
of  the  -body  of  the  same  individual.  It  may  be  deep 


ENTOMOSTRACA  AND  PHYLLOPODA.       253 

red,  brilliant  purple,  bluish  with  purple-tipped  antennae, 
whitish,  or  colorless.  The  animals  may  be  found  in 
shallow  pools  in  the  fall  and  early  spring,  and  occasion- 
ally in  slowly  flowing  streams.  The  external  ovary  is 
single. 

11.  CANTHOCAMPTUS  (Fig.  166). 

After  Cyclops  and  Daphnia  this  is  the  commonest 
fresh-water  Entomostracan  in  the  writer's  vicinity.  A 
gathering  of  aquatic  plants  can  seldom  be  made  in  this 
neighborhood  without  obtaining  many  of  the  graceful 
little  Canthocampti.  They  are  visible  to  the  unaided  eye 
as  small,  flesh-colored,  or  pinkish  lines  darting  through 
the  water  in  short  jerks,  after  the  manner  of  most  En- 
tomostraca.  Like  all  minute  animals,  they  will  collect 
on  the  best  lighted  side  of  the  bottle,  where  they  may 
be  easily  captured  with  the  dipping-tube.  The  eye  is 
single.  The  antennae  are  short  and  quite  hairy.  The 
body  is  long,  narrow,  and  sub- 
cylindrical,  being  widest  and 
thickest  in  front.  There  is  no 
distinct  heart.  The  external  Fig.166._Canthoc,mptus. 
ovary  is  single.  It  is  attached 

to  the  parent  by  the  thinnest  and  apparently  most  deli- 
cate part,  although  considerable  force  is  necessary  to 
separate  it  from  the  body.  The  eggs  are  round  and 
opaque.  The  young  differ  greatly  from  their  mature 
aspect.  Canthocamptus  is  found  in  almost  any  shallow 
body  of  still  water,  and  all  the  year  through,  even  occa- 
sionally in  midwinter.  It  is  shown  in  side  view  in  the 


254:  MICROSCOPY  FOR  BEGINNERS. 

figure,  so  as  to  exhibit  the  single  external  ovary  so 
characteristic  of  it. 

12.  CYCLOPS  (Figs.  167, 167a). 

This  commonest  of  all  fresh-water  Entomostraca  has 
a  single  eye  in  the  middle  of  the  forehead,  like  the 
giants  of  ancient  story,  a  bifid  tail  adapted  for  swim- 
ming, and  two  external  ovaries, 
one  on  each  side.  These  ovaries 
are  long,  pear-shaped  sacks  filled 
with  dark,  opaque  eggs,  and  at- 
tached to  the  body  by  the  narrow 
or  stem  end  of  the  pear.  The 
young  (Fig.  16 70)  pass  through 

Fig.  1<>7.— Cyclops.  ,      .  .      . 

several  stages  before  they  begin 

to  resemble  the  parent.  It  lias  been  said  that  the  eggs 
are  carried  in  the  external  ovaries  only  until  they  are 
ready  to  hatch,  when  they  are  deposited  before  the 
young  make  their  escape.  This  is  a  mistake,  as  the 
student  will  probably  soon  observe.  The 
young  leave  the  eggs  while  they  are  still 
attached  to  the  parent.  They  break  the 
egg  membrane  very  suddenly  and  unex- 

.j,          i  ,  ,  ,  •.  Young  Cyclops. 

pectedly,  although  the  observer  may  have 
been  for  some  time  watching  the  little  creatures  rest- 
lessly moving  about  inside.     As  they  escape  they  often 
dart  half-way  across  the  field  of  a  low-power  objective. 
•    If  Cyclops  had  no  enemies  the  waters  would  soon 
become  filled  with  them  in  numbers  almost  beyond  im- 


ENTOMOSTRACA  AND  PHYLLOPODA.       255 

agining.  One  female  Cyclops  has  been  seen  to  lay  ten 
times  in  succession ;  but,  to  be  within  bounds,  the  ob- 
server who  made  the  calculation  supposes  a  single  one 
to  lay  eight  times  only,  and  forty  eggs  at  each  time. 
"  At  the  end  of  one  year  this  female  would  have  been 
the  progenitor  of  4, 442,189,120  young- — :that  is,  near 
four  and  a  half  thousands  of  millions." 

There  are  about  thirty  species  of  Cyclops,  and  in  all 
of  them  there  are  four  antennas,  two  being  long  and 
conspicuous,  the  other  two  small,  and  often  carried  so 
that  they  are  invisible  unless  the  Cyclops  is  turned  on 
its  back. 

PHYLLOPODA. 

13.  LIMNETIS  (Fig.  168). 

The  oval  or  nearly  spherical,  smooth  shell  has  a  well- 
marked  beak,  which  in  some  of  the  species  is  enor- 
mous, while  in  others  it  is  less  conspicuous.  "When  the 
valves  are  closed  they  measure  about 
one-sixth  of  an  inch  in  length,  and 
have  often  been  mistaken  for  small 
fresh-water  mollusks  of  the  genus  Pi- 

Fig.  16S.-Limn6tis. 

sidium.  The  eyes  are  two,  but  so 
close  together  that  they  often  appear  to  be  united ;  they 
are  black.  The  animals  swim  on  the  back,  as  do  so 
many  of  the  Phyllopoda.  In  the  males  the  two  front 
legs  are  flattened,  and  have  on  the  end  of  each  a  compli- 
cated organ  called  the  hand,  although  it  bears  the  most 
remote  resemblance  to  the  human  hand.  The  eggs  are 


256  MICROSCOPY  FOR  BEGINNERS. 

carried  on  the  back  under  the  shell.     The  animals  are 
flesh  color. 

14.  ESTHEIUA. 

The  shell  is  smooth  and  shining,  and  marked  with  dis- 
tinct lines  running  almost  parallel  with  the  front,  or 
free  edge,  of  the  valves.  It  is  very  thin,  flat,  and  large, 
measuring  about  two-thirds  of  an  inch  in  length.  The 
males  have  two  pairs  of  hands,  or  one  on  each  of  the 
four  front  legs.  The  shell  of  the  several  species  varies 
from  oval  to  oblong  with  the  upper  margin  very  much 
flattened,  or  it  may  be  somewhat  globose.  Most  of  the 
species  are  confined  to  the  waters  west  of  the  Missis- 
sippi River,  one,  however  (Estheria  Mexicdna\  being 
found  near  Cincinnati.  Many  of  them  are  in  appear- 
ance not  unlike  a  small  clam,  or  the  little  fresh-water 
mollusk,  Pisidium,  so  common  almost  everywhere. 

15    ARTEMIA  (Fig.  169). 

Artemia  occurs  only  in  brine  or  the  water  of  salt 
lakes.     It  is  not  rarely  found  in  the  hogs- 
heads of  water  on  railroad  bridges  or  tres- 
tles, where  the  water  is  made  salt  to  pre- 
vent freezing.     The  bodies  are  slender 
and  pale  red,  flesh -color,  or   sometimes 
greenish.    The  feet  are  eleven  pairs,  beau- 
tifully fringed  with  many  long  hairs,  and 
P5   169— Artomia    Bearing  the  flattened  branchial  or  breath- 
(a  female).         ing-plates.     When  the  creature  swims  on 
its  back,  as  it  habitually  does,  these  feathery  feet  beat 


ENTOMOSTRACA  AND  PHYLLOPODA.  257 

the  water  in  rapid  succession,  as  if  a  wave  of  motion 
were  rapidly  passing  above  them.  It  is  a  beautiful  creat- 
ure, and  one  sure  to  attract  attention,  not  only  by  its 
graceful  motions  and  preference  for  salt  water,  but  by 
its  size,  being  half  an  inch  or  more  in  length.  The  eyes 
are  black,  and  placed  on  the  ends  of  stalks  projecting 
from  each  side  of  the  rather  small  head.  The  antennae 
are  short,  but  conspicuous.  The  eggs  are  yellowish- 
white.  The  young  are  very  active,  and  differ  much  in 
appearance  from  the  parent.  They  are  blood  red,  with 
one  bluish  eye. 

16.  CHIROCKPHALUS. 

This  curious  creature  has  eleven  pairs  of  swimming 
feet,  as  has  Branch'ipus,  but  there  need  be  no  difficulty 
in  distinguishing  it  from  Branchipus  (for  which  it  may 
be  mistaken)  provided  the  male  is  obtained.  If  the  fe- 
male alone  is  captured  some  trouble  may  be  experienced 
by  the  beginner  in  determining  one  from  the  other. 
The  female  of  Chirocephalus,  however,  is  slender,  while 
that  of  Branchipus  is  stout ;  but  such  a  distinction  is 
valueless  until  both  have  been  seen,  or  the  two  sexes 
have  been  taken  from  the  same  pond.  In  the  latter 
case  the  male  may  be  known  by  the  two  remarkable  ap- 
pendages hanging  down  from  the  sides  of  the  head. 
These  are  about  one-fourth  of  an  inch  long  when  ex- 
tended, and  are  curved  and  coiled  and  twisted  in  a  way 
that  defies  description.  Each  one  is  broad  near  the  up- 
per or  attached  ends,  and  diminishes  to  a  long,  curved 
point  covered  with  minute  spines,  while  in  its  entire 


258  .      MICROSCOPY   FOR  BEGINNERS. 

length  it  is  curiously  lobed.  The  egg-sack  of  the  fe- 
male is  short  and  small,  and  the  attached  end  is  length- 
ened, somewhat  like  the  neck  of  a  bottle.  The  eggs  are 
very  large,  and  about  twelve  in  number.  The  body  of 
each  sex  is  about  two-thirds  of  an  inch  long.  Chiro- 
cephalus  is  often  found  in  company  with  Branchipus, 
usually  in  the  spring,  as  early  as  the  middle  of  March. 

17.  BRANCHIPUS  (Fig.  170). 

The  flesh-colored  or  pale  red  body  is  stout  and  large, 
often  measuring  an  inch  in  length.     The  head  is  large, 
and  the  frontal  appendages  of  the  male  are  long  and 
broad,  as  shown  enlarged  In  Fig.  170.    These  hang  down 
on   each  '  side   of  the  head, 
and  are  formed  of  two  quite 
dissimilar  parts.    The  upper 
half  is  broad  and  thick,  and 
Fig. m-Branchipus  about  one- fifth  of  an  inch 

(a  male). 

long.     It  ends   in   a  stiff, 

bristle-like  prolongation  of  nearly  equal  length,  with  a 
short,  bristle-like  tooth  at  the  inner  side  at  the  point  of 
junction  of  the  two  parts.  There  are  eleven  pairs  of 
swimming  feet,  and  the  animal  swims  on  the  back.  The 
eyes  are  two,  black,  and  elevated  on  the  ends  of  short 
stalks.  The  body  of  the  female  is  as  large  and  as  stout 
as  that  of  the  male.  The  egg-sack  is  noticeable  near  the 
point  of  union  between  the  posterior  narrow  portion  of 
the  body  and  the  broader  front. 

It  is  a  curious  fact  that  Branchipus  is  killed  by  even 


ENTOMOSTRACA  AND  PHYLLOPODA.       259 

the  heat  of  early  summer  or  late  spring.  Dr.  Packard, 
describing  a  visit  to  a  pond  where  these  creatures  had 
been  found  on  May  2d,  but  from  which  they  had  all 
disappeared  by  May  13th,  says,  "  It  seems  from  this 
quite  evident  that  the  animal  probably  dies  off  at  the 
approach  of  warm  weather,  and  does  not  reappear  until 
after  cool  weather  sets  in  late  in  the  autumn,  being  rep- 
resented in  the  summer  by  the  eggs  alone;  and  thus 
the  appearance  and  disappearance  of  this  Phyllopod  is 
apparently  determined  mainly  by  the  temperature." 

A  vessel  full  of  water  in  which  Branchipus  is  floating 
on  its  back  is  a  strangely  beautiful  and  interesting  sight. 
The  pale  reddish  or  flesh-colored  bodies  rising  and  fall- 
ing in  long  curves,  with  their  numerous  broad  feet 
waving  together  rhythmically,  make  a  living  picture 
long  to  be  pleasantly  remembered. 

Those  readers  who  desire  to  pursue  the  subject,  es- 
pecially in  respect  to  the  anatomy  and  development  of 
these  crustaceans,  are  referred  to  Mr.  C.  L.  Herrick's 
"  Crustacea  of  Minnesota,"  published  in  the  twelfth  an- 
nual report  of  the  State  Geologist,  and  to  Prof.  A.  S. 
Packard's  "  Monograph  of  the  Phyllopod  Crustacea  of 
North  America,"  issued  in  the  twelfth  annual  report 
of  the  United  States  Geological  and  Geographical  Sur- 
vey of  the  Territories,  Dr.  F.  V.  Hayden  in  charge. 
12* 


260  MICROSCOPY  FOR  BEGINNERS. 


CHAPTER  XL 

WATER-MITES   AND   THE   WATER-BEAK. 

THE  Water-mites  (Fig.  171)  are  sometimes  called  wa- 
ter-spiders, probably  because  they  bear  some  resemblance 
to  small  spiders,  and  have  eight  legs.  Naturalists  have 
seen  the  resemblance  and  have  placed  them  in  a  family 
group  near  to  the  spiders.  Water-spider,  however,  is 
not  a  good  name  for  them,  as  we  have  some  true  spiders 
that  are  semi-aquatic  in  their  habits  and  have  therefore 
a  better  title  to  such  a  name. 

The  water-mites  are  usually  very  active  little  animals, 
swimming  freely  and  rapidly  through  the  water,  or 
forcing  themselves  among  the  leaflets  of  aquatic  plants, 
probably  in  search  of  food.  They  may  generally  be 
obtained  in  some  abundance  by 
collecting  water -weeds  in  the 
way  previously  recommended, 
namely,  by  sinking  the  bottle 
and  floating  the  plants  into  it 
without  removing  them  from 

.,./*,  m,  Fig.  171.— A  Water-mite. 

their  native  element.     They  are 

all  quite  visible  to  the  unaided  eye,  and  may  for  the 

most  part  be  studied  with  a  comparatively  low-power 

objective. 

Their  bodies  are  plump  and  oval,  or  nearly  spherical. 


WATER-MITES  AND  THE   WATER-BEAR.  261 

The  skin  of  most  of  the  forms  is  soft  and  easily  broken, 
but  in  the  members  of  a  single  genus,  Arrenurus,  the 
surface  is  firm  and  comparatively  hard.  They  are  all 
brightly,  even  brilliantly,  colored.  They  may  be  of  one 
uniform  tint,  with  a  few  blackish  or  brownish  spots  on 
the  posterior  region,  or  the  single  individual  may  be 
variously  tinged  in  different  parts  of  the  body.  The 
colors  are  of  almost  every  imaginable  shade  of  crimson, 
azure  blue,  yellow,  green,  brown,  gray,  or  purple.  The 
eight  long  legs  also  share  in  the  general  brilliancy,  and 
often  present  a  coloration  entirely  different  from  that 
of  the  body. 

The  eyes  are  usually  on  the  upper  surface  near  the 
front  border.  They  are  small,  and  may  be  either  round 
or  crescentic  in  shape,  red,  black,  or  carmine  in  color, 
and  two  or  four  in  number.  They  are  usually  placed 
close  together,  and  when  four  in  number,  are  arranged 
in  two  distinct  pairs. 

The  upper  part  or  the  back  of  the  little  animals  may 
be  entirely  smooth,  densely  clothed  with  short  hairs,  or 
with  a  few  scattered,  fine  bristles.  It  may  also  present 
no  markings  when  magnified,  or,  as  in  a  single  genus, 
Arrenurus,  it  may  be  beautifully  ornamented  with  a 
net-work  of  narrow  meshes  in  a  hexagonal  pattern.  In 
all,  or  nearly  all,  of  the  mites  the  upper  surface  bears 
two  or  more  black,  dark  brown,  or  reddish  spots  quite 
distinct  from  the  general  coloring  of  the  body.  These 
are  caused  by  nearness  to  the  surface  of  the  intestine  or 
other  internal  viscera,  the  dark  contents  of  which  show 


262  .          MICROSCOPY  FOR  BEGINNERS. 

their  color  through  the  skin.  In  some  these  dark  spots 
become  large,  occupying  much  of  the  upper  surface,  and 
so  arranged  and  shaped  that  they  leave  between  them 
in  the  middle  line  of  the  body  a  Y-shaped  space  which 
may  be  white,  yellow,  or  other  color.  These  spots  are 
called  cosca  or  the  ccecal  markings,  the  word  being  the 
plural  of  ccecum,  meaning  a  certain  part  of  the  intestinal 
canal.  They  are  useful  to  the  student  in  identifying 
the  species. 

The  lower  or  ventral  surface  is  the  most  important 
part  to  the  observer  who  desires  to  ascertain  the  name 
of  his  specimen,  or  to  the  student  who  wishes  to  make 
a  more  serious  study  of  the  animals,  for  on  this  surface 
are  the  parts  most  used  by  the  naturalist  in  classifying 
the  mites.  The  beginner  must  therefore  seek  to  have 
the  little  creature  arranged  on  its  back  before  it  is 
placed  under  the  microscope,  so  that  the  ventral  surface 
shall  be  presented  to  the  objective.  This  is  sometimes 
a  difficult  operation  to  accomplish  without  injuring  the 
delicate  body.  The  writer  has  used  for  the  purpose  a 
little  home-made  contrivance  that  answers  well  and  can 
be  made  by  any  one.  A  hole  about  half  an  inch  in  di- 
ameter is  drilled  through  a  glass  slip,  and  into  one  side 
is  cemented  with  shellac  a  thin  glass  circular  cover  a 
little  smaller  than  the  hole,  so  that  the  thin  cover  may 
not  be  flush  with  the  surface  of  the  slip.  It  is  not 
very  difficult  to  grind  a  hole  through  a  thin  glass  slip 
if  the  file  or  other  grinding  tool  is  kept  wet  with  tur- 
pentine. The  aperture  may  not  be  a  perfect  circle;  it 


WATER-MITES   AND  THE   WATER-BEAR.  263 

will  probably  be  very  irregular — I  know  mine  is — but  it 
will  answer  every  purpose.  The  mite  is  placed  in  this 
cell,  and  a  thin  cover  applied  to  the  opposite  side,  thus 
forming  a  glass  box  that  can  be  turned  over  for  the  ex- 
amination of  both  surfaces  of  the  animal,  and  is  deep 
enough  not  to  injure  the  soft  body,  yet  shallow  enough 
to  restrain  its  movements. 

The  mouth  of  the  mite  is  usually  a  complicated  affair, 
and  is  sometimes  surrounded  by  a  circular  elevation  or 
ring  called  a  hood,  and  always  having  short,  jointed 
palpi,  or  feelers.  At  some  distance  back  of  the  mouth, 
in  some  forms  quite  near  to  the  posterior  border,  but 
always  in  the  median  line,  will  be  seen  in  the  female 
mites  a  small  dark  spot  or  narrow  line  which  is  really 
an  opening.  In  some  this  orifice,  which  may  be  called 
the  ventral  opening,  is  covered  and  concealed  by  a  large 
plate,  called  the  ventral  plate ;  or  there  may  be  two 
plates,  curved,  oval,  or  other  shape,  one  on  each  side  of 
the  ventral  opening.  They  are  useful  to  the  naturalist 
as  one  means  by  which  the  mites  may  be  classified,  and 
they  should  be  carefully  searched  for  by  the  beginner 
who  desires  to  learn  the  name  of  his  specimen.  They 
are  not  present  in  the  males.  The  reader  will  therefore 
perceive  that  to  identify  his  captive  the  specimen  must 
be  a  female.  The  two  sexes,  however,  differ  so  con- 
spicuously in  appearance  that  they  are  easily  recognized. 
The  female  always  has  the  posterior  border  of  the  body 
more  or  less  evenly  rounded,  while  the  male  frequently 
possesses  a  peculiar  little  tail -like  process  projecting 


264  MICROSCOPY  FOR  BEGINNERS. 

from  the  middle  of  the  rear  margin.  One  form  of  this 
curious  projection  is  shown  in  Fig.  176,  a  female  by 
Fig.  171,  the  projection  varying  in  shape  and  size  in 
the  different  species.  The  males  seem  much  less  abun- 
dant than  the  females ;  they  are,  at  least,  less  frequently 
captured  by  the  microscopical  fisherman. 

On  the  ventral  surface,  behind  or  before,  or  on  both 
sides  of  the  ventral  plates,  will  be  observed  one  or  more 
very  small  dark  spots  never  bordered  by  a  plate.  These 
are  the  external  openings  of  the  tracheae  or  air-tubes, 
which  extend  through  the  body  and  supply  it  with  oxy- 
gen. As  the  mites  are  not  known  to  come  to  the  sur- 
face for  a  supply  of  air,  as  so  many  aquatic  animals  do, 
the  tracheae  are  supposed  to  be  able  to  absorb  it  directly 
from  the  water.  The  tracheal  openings  are  not  an  im- 
portant aid  in  ascertaining  the  name  of  the  creature,  but 
the  beginner  must  not  mistake  them  for  the  aperture 
bordered  or  covered  by  the  ventral  plates.  In  some 
mites  they  are  not  well  marked,  and  may  be  overlooked, 
and  there  is  still  another  dark  spot  usually  present  near 
the  posterior  part  of  the  ventral  surface  which  must  not 
be  confounded  with  the  ventral  opening  since  it  is  in 
the  median  line.  This  is  the  external  opening  of  the 
intestine.  It  is  never  bordered  by  plates,  and  is  always 
behind  the  ventral  orifice,  but  it  is  not  always  con- 
spicuous. 

Equally  important  to  the  student  are  certain  eleva- 
tions of  the  ventral  surface  which  appear  to  cover  the 
attached  ends  of  the  legs.  These  are  called  the  coxa, 


WATER-MITES  AND   THE   WATER-BEAR.  265 

the  plural  of  coxa,  a  Latin  word  meaning  the  thigh. 
They  are  variously  shaped  and  arranged,  one  coxa  seem- 
ing to  cover  the  end  of  each  leg,  or  appearing  to  be  the 
thigh  belonging  to  that  leg.  They  are  motionless,  how- 
ever, and  are  really  only  elevations  of  the  skin,  beneath 
which  the  muscles  of  the  legs  may  be  seen  in  action. 
In  some  mites  the  coxae  on  each  side  of  the  body  are 
arranged  in  groups  of  two  each,  the  borders  of  the  two 
which  form  the  group  being  in  contact  either  by  their 
whole  length,  as  in  Figs.  175,  176,  and  177,  or  only  at 
some  single  point,  as  in  the  posterior  group  shown  in 
Fig.  174.  In  Figs.  174, 175, 176,  and  177  there  are  four 
groups,  formed  of  two  coxae  each ;  in  Fig.  173  there  are 
six  groups,  the  anterior  alone  being  formed  of  two,  the 
two  posterior  groups  on  each  side  being  of  but  one  coxa 
each  and  separated.  Their  shape  differs  widely  even  in 
the  species  of  one  genus ;  their  arrangement,  however, 
is  constant  and  important. 

The  eight  legs  are  long  and  jointed,  the  last  joint 
ending  in  one  or  two  short  claws.  The  hairs  fringing 
their  margins  are  long  and  numerous,  and  are  used  as 
aids  in  swimming.  They  add  a  good  deal  to  the  beauty 
of  the  animal. 

Mites  are  found  in  salt  as  well  as  in  fresh  water,  but 
with  the  marine  forms  this  little  book  has  nothing  to 
do.  The  fresh-water  ones  are  propagated  by  means  of 
eggs,  which  are  often  seen  attached  to  the  stems  of 
aquatic  plants  or  to  the  lower  surface  of  floating  leaves, 
where  the  writer  has  obtained  them  and  had  them  to 


,266  MICROSCOPY  FOR  BEGINNERS. 

hatch  in  captivity.  They  are  small,  brownish,  jelly 
masses,  which  might  easily  be  overlooked  or  passed  by 
as  snails'  eggs,  often  to  be  found  in  the  same  localities. 
The  newly-hatched  young  often  bear  but  a  slight  re- 
semblance to  the  parents,  those  of  some  genera  having 
but  six  legs,  those  of  one  species  being  said  to  have  but 
three.  Many  of  these  immature  forms  are  parasitic  on 
aquatic  insects,  becoming  free-swimming  and  independ- 
ent when  they  attain  adult  growth  and  age.  Some  of 
the  mature  mites  are  also  parasitic  in  the  gills  of  the 
fresh- water  mussel  (Unio}.  On  account  of  these  pecu- 
liarities the  study  of  their  life  history  is  a  difficult  one. 

The  Entomostraca  and  Infusoria  are  said  to  form 
their  favorite  food. 

There  may  seem  to  be  but  little  connection  between 
the  water-mites  and  the  water-bear,  and  still  less  resem- 
blance, yet  naturalists  have  classified  them  near  together. 
The  water -bear  (Fig.  172)  is  a  common  and  curious 
aquatic  animal,  so  closely  and  so  comically  resembling  a 
transparent  eight-legged  microscopic  bear  that  the  be- 
ginner will  know  it  the  first  time  he  sees  it ;  further  ref- 
erence to  it  is  therefore  reserved  for  another  page 
(p.  267). 

Key  to  Genera  of  the  Water-mites  (Hydrachnidce). 

1.  Body  colorless,  cylindrical,  elongated,  and  transpa- 
rent ;  legs  eight,  short,  with  claws ;  the  animal 
walks  slowly  and  is  bear -like  in  appearance.  Wa- 
ter-bear (Macrobi6tus\  1. 


WATER-MITES  AND  THE  WATER-BEAR.  267 

2.  Body  brightly  colored,  oval,  or  spherical ;  legs  eight, 

long ;  animal  swimming  actively  (a). 

3.  Body  brightly  colored,  oval,  or  spherical ;  legs  eight, 

long ;  animal  walking,  never  swimming  (e). 

a.  Ventral  plate  single,  cordate,  the  apex  pointing  for- 
ward. Diplodontus.,  2. 

a.  Ventral  plate  single,  cordate,  the  apex  rounded, 
pointing  backward  (5). 

a.  Yentral  plate  double  (c). 

b.  Posterior  coxae  on  the  same  side  not  in  contact. 

Hydrdchna,  3. 

c.  Posterior  coxae  on  the  same  side  in  contact  by  their 

whole  length  (d). 

c.  Posterior  coxae  on  the  same  side  in  contact  only  by 

their  internal  ends,  their  outer  extremities  di- 
verging.   Eyldis,  4. 

d.  Yentral  plates  oval,  with  an  oval  plate  on  each  side ; 

mouth   round,  with  a  circular  hood.     Arrenu- 
rus,  5. 

d.  Yentral  plates  narrow,  curved,  each  with  two  or 

three  translucent  tubercles.     Atax,  6. 

e.  Eyes  four,  on  a  lanceolate  plate;   coxae  in  four 

groups.     Limnochares,  7. 

1.  THE  WATER-BEAR:  Macrobibtus  (Fig.  172). 

The  body -is  soft,  colorless,  and  transparent.     The  legs 

are  very  short,  and  have  on  the  end  of  each  several  sharp 

claws,  the  legs  being  arranged  three  on  each  side  of  the 

body  and  two  at  or  near  the  posterior,  extremity.     The 


268  MICROSCOPY  FOR  BEGINNERS. 

mouth  is  a  small  opening  at  the  front  of  the  part  repre- 
senting the  head.  It  is  followed  internally  by  two  short, 
somewhat  curved  and  diverging  rods,  said  to  be  used  to 
wound  the  prey.  The  so-called  gizzard,  at  a  short  dis- 
tance from  the  mouth,  is  plainly  visible  through  the 
transparent  body.  It  has  no  motion.  Two  small  eyes 
are  usually  present,  one  on  each  side  of  the  head.  The 
animal's  movements  are  very  slow  and  awk- 
ward, the  creature  appearing  to  work  hard, 
with  but  little  result  so  far  as  progress  is 
concerned. 

Macrobiotus  is  produced  by  eggs,  which 
water-bear      are  deposited  in  an  interesting  way.    When 

(Mncrobi6tus). 

they  are  suinciently  matured,  the  water-bear 
sheds  its  skin  and  leaves  the  eggs  in  the  empty  and  cast- 
off  case.  It  is  no  unusual  occurrence  to  find  the  empty 
skin  of  Macrobiotus  with  the  empty  eggs  inside,  the 
young  having  escaped.  The  young  resemble  the  par- 
ent, it  is  said,  in  all  except  size. 

This  strange,  bear-like  creature  is  to  be  found  quite 
often  at  the  bottom  of  shallow  ponds ;  or,  if  an  aquari- 
um is  kept,  it  will  be  almost  sure  to  make  the  bottom 
its  home.  It  is  entirely  invisible  to  the  naked  eye,  meas- 
uring rather  less  than  one-sixtieth  of  an  inch  in  length. 
On  account  of  their  slow  movements,  the  water-bears 
are  often  called  Tardigrades.  The  scientific  name  of 
the  common  American  form  is  Macrobiotus  Ameri- 
ctinus. 


WATER-MITES  AND  THE   WATER-BEAR.  269 

2.    DlPLODONTUS. 

This  mite  may  be  recognized  by  the  form  of  the  ven- 
tral plate  as  given  in  the  Key,  and  by  the  fact  that  the 
plate  is  roughened  by  minute  granules.  The  eyes  in 
one  species  are  two  in  number,  very  small,  and  wide 
apart.  They  are  placed  on  the  edge  of  the  front  border. 
In  another  species  they  are  four,  and  are  placed  so  far 
forward  on  the  front  margin  that  they  are  best'  seen 
when  the  animal  is  on  its  back,  and  thus  examined  from 
beneath.  The  coxae  are  in  four  separate  groups.  The 
body  of  the  two-eyed  species  has  the  front  part  black, 
spotted  with  red,  and  the  posterior  half  red,  with  a  central 
longitudinal  black  band.  The  one  with  four  eyes  has  the 
body  bright  red. 

3.  HYDRACHNA  (Fig.  173). 

The  anterior  coxae  on  the  same  side  form  a  single 
group,  being  in  contact  by  their  whole  length;  the  mid- 
dle one  is  entirely  disconnected  from  the 
others ;  the  most  posterior  is  the  largest, 
and  is  also  entirely  separate.  In  one 
species  the  body  is  spherical  and  black, 
with  yellow  dots,  the  legs  being  shorter  Fig.  ITS.— coxse  of 
than  the  body,  and  black,  with  red  ends. 
In  another  the  body  is  red,  with  two  pairs  of  dark  red 
eyes,  and  long  legs.  The  young  are  said  to  have  but 

three  legs. 

4.  EYLAIS  (Fig.  174). 

The  two  anterior  coxse  are  in  contact  by  their  entire 
length,  and  form  one  group  on  each  side.  The  two 


270  MICROSCOPY  FOR  BEGINNERS. 

posterior  coxse  are  in  contact  only  as  described  in  the 
Key.  They  are  all  moderately  narrow.  The  mouth  is 
round,  ciliated,  and  with  a  kind  of  hood  which  the  be- 
ginner may  have  some  trouble  to  recognize. 
The  ventral  plates  are  curved,  almost  cres- 
centic,  and  narrow,  one  being  on  each  side 
of  the  ventral  opening,  and  just  behind  them 
are  two  small  tracheal  apertures.  The  in- 

Fi<?-  174.—  Coxae    ...      i         «.c         •         -MI         ,    ,1  .1 

testmal  orifice  is  visible  at  the  rear  in  the 


middle  line,  with  a  tracheal  opening  on  each 
side.  The  eyes  are  four,  in  two  pairs,  rather  close  to- 
gether. A  large  red,  nearly  spherical  JEyldis  is  quite 
common  in  our  ponds.  The  young  are  described  as 
being  red,  transparent,  with  four  eyes  wide  apart,  and 
six  legs. 

5.  ARRENTJRUS  (Figs.  175,  176). 

The  coxse  form  two  groups  on  each  side,  the  two  an- 
terior coxae  being  in  contact  by  their  entire  length,  as 
are  also  the  two  posterior.  Occasionally  the  anterior 
groups  on  opposite  sides  are  in  contact  at 
the  median  line,  as  in  Fig.  175.  The  ventral 
plates  are  oval,  their  greatest  length  gener- 
ally being  from  before  backward,  and  usu- 
ally close  together.  The  two  oval,  lateral 

Fig.  175.  -Coxae         J 

of  Arreuurus     plates  are  oval  from  side  to  side,  and  some- 

times curved.     The  mouth  is  small,  round, 

and  encircled  by  a  ring-like  hood.     The  skin  is  usually 

hard  and  roughened,  or  covered  by  a  deep  net  -work 

of  strongly  elevated   lines,  which  give   it  a  beautiful 


WATER-MITES  AND  THE  WATER-BEAR.  271 

appearance.  The  skin  is  sometimes  shed  in  captivity, 
and  is  not  rarely  found  as  a  torn,  empty,  and  colorless 
net,  quite  worth  examining  with  a  high  power.  There 
are  some  soft-bodied  species,  but  they  do  not  seem  to 
be  common. 

The  body  of  both  the  male  and  female  is  truncated 
at  the  posterior  border,  but  the  male  has  a 
peculiar  short  prolongation  projecting  from 
the  centre  of  that  margin,  as  in  Fig.  176,  the 
shape  of  the  part  varying  greatly  in  the  dif- 
ferent species.  The  females  are  the  most 
numerous  and  most  frequently  met  with, 
The  upper  surface  or  back  of  both  sexes 
often  bears  a  deep,  depressed  line,  sometimes  enclosing 
a  small  circular  or  oval  area  confined  to  the  posterior 
extremity,  sometimes  a  large  space,  including  the  great- 
er part  of  the  entire  back.  From  others  it  may  be  ab- 
sent. The  eyes  are  two,  black,  and  separated.  The 
color  of  the  body  is  very  different  in  the  numerous  spe- 
cies. It  may  be  blue,  green,  yellow,  red,  or  almost  any 
bright  tint,  either  diffused  or  confined  to  distinct  parts. 
Thus  in  one  female  the  centre  of  the  body  is  brown,  the 
sides  blue,  and  the  coxae  yellow.  In  another  the  body  is 
red,  the  coeca  vermilion.  Another,  a  male,  has  a  bright 
yellow  tail,  the  centre  of  the  body  white,  with  a  blue 
line  near  the  posterior  border,  and  dark  brown  coeca. 

A  species  of  Arrenurus  with  a  hard  and  reticulated 
surface  is  not  uncommonly  captured  among  Ceratophyl- 
lura  and  Myriophyllum  in  rather  shady  places  which, 


272  MICROSCOPY  FOR  BEGINNERS. 

I  think,  all  the  water -mites  prefer.  A  moment's  ex- 
posure to  the  direct  sunlight  out  of  the  water  is 
fatal. 

6.  ITAX  (Fig.  177). 

The  anterior  coxse  are  in  contact  by  their  entire 
length,  and  the  posterior  extremities  of  the  two  anterior 
groups  on  each  side  are  also  often  in  contact,  thus  ap- 
pearing to  press  the  mouth  between  them.  The  posterior 
coxse  are  also  in  contact  for  their  whole  length,  but  they 
do  not  touch  those  of  the  opposite  side  of  the  body.  The 
fourth  coxa,  or  the  one  belonging  to  the 
most  posterior  leg,  is  usually  much  larger 
and  broader  than  any  of  the  others.  The 
two  ventral  plates  are  narrow  and  curved, 
^ie  tubercles  on  each  of  them  being  round- 
ed and  translucent.  The  front  pair  of  legs 
are  long  and  curved,  the  hairs  on  them  being  bristle- 
like.  When  the  mite  walks  these  legs  are  held  rigidly 
in  front.  The  color  of  the  body  varies,  as  it  does  in  the 
other  forms.  A  yellow  Atax  is  not  uncommon  in  our 
ponds  and  shallow,  slowly  flowing  streams. 

7.  LIMNOCHARES  (Fig.  178). 

This  mite  may  be  recognized  by  its  habit  of  always 
walking.  It  never  swims.  In  this  it  differs  from  all 
the  other  known  forms  of  fresh-water  mites.  The  eyes 
are  four,  and  are  arranged  on  a  lanceolate  plate  (Fig. 
178,  much  enlarged),  two  on  each  side,  with  a  central 
rounded  projection  between  them  in  front.  They  are 


WATER-MITES  AND  THE  WATER-BEAR.  273 

also  surrounded  by  hairs.     The  coxse  do  not  make  the 

prominent  elevations  common  to  the  other  mites,  but 

seem  rather  to  be  beneath  the  skin.    "  The 

coxae  of  the  anterior  two  pairs  of  legs  are 

closely  approximate,  as   are  also  those  of 

the  two  posterior  pairs,  but  the  two  groups 

are  widely  separated."     The   anterior  are 

larger  than  the  posterior.     The  mites  are 

small.     I  have  never  been  so  fortunate  as  to  meet  with 

Limnochares  nor  with  Diplodontus. 

If  the  observer  should  desire  to  make  permanently 
mounted  slides  of  his  specimens  of  mites,  he  may  try 
a  preservative  medium  prepared  by  mixing  eight  parts 
of  water  containing  a  drop  or  two  of  carbolic  acid,  with 
one  part  of  glycerine.  This  is  said  to  keep  the  bodies 
without  the  loss  of  their  characteristic  plumpness,  nor 
much  of  their  color,  if  mounted  in  a  deep  cell.  Two 
specimens  should,  if  possible,  be  preserved  in  the  same 
cell,  and  so  arranged  as  to  show  both  surfaces.  They 
will  usually  need  a  large  and  deep  ring. 

The  fresh -water  mites  have  never  been  studied  by 
any  American  naturalist ;  there  are,  therefore,  no  books 
nor  even  isolated  papers  to  which  the  beginner  may  be 
referred  for  further  aid.  The  field  is  an  entirely  unex- 
plored one  so  far  as  the  water-mites  of  this  country  are 
concerned.  To  a  student  with  an  eye  sensitive  to  color, 
and  with  a  large  amount  of  patience,  the  subject  ought 
to  be  an  attractive  one. 


274:  MICROSCOPY  FOR  BEGIIsNERS. 


CHAPTER  XII. 

SOME   COMMON   OBJECTS   WORTH    EXAMINING. 

THERE  is  literally  no  end  to  the  objects  worth  exam- 
ining with  the  microscope.  Even  a  pocket -lens  re- 
veals new  and  wondrous  aspects  in  the  most  familiar 
things.  An  old  and  leathery  lichen  from  a  stump  be- 
comes a  charming  picture  and  a  living  one,  for  its  hills 
and  hollows  and  winding  valleys  are  the  homes  and 
hiding-places  of  innumerable  little  creatures  which  the 
pocket-lens  brings  to  view.  -  The  furrowed  and  weather- 
worn bark  of  any  tree  has  countless  points  of  interest 
and  charm.  Neither  need  there  be  any  scarcity  of  ma- 
terial at  any  season  of  the  year.  In  the  spring  and  sum- 
mer the  only  trouble  is  to  find  the  time  to  examine  even 
a  small  portion  of  all  the  wondrous  and  beautiful  things 
that  nature  then  offers.  In  midwinter,  life  and  beauty 
are  almost  as  abundant,  if  less  conspicuous.  The  dust 
swept  by  a  feather  from  the  wall  of  a  dark  cellar  may 
bring  to  light  minute  creatures  not  to  be  obtained  else- 
where. There  is  no  end  to  the  objects,  there  is  no  end 
to  the  unlikely  places  that  will  reward  a  little  search, 
and  there  is  no  end  to  the  telling,  unless  it  be  an  abrupt 
one. 

But  although  the  beginner  may  never  be  at  a  loss  for 


COMMON   OBJECTS  WORTH  EXAMINING.  275 

employment  for  his  pocket-lens,  he  may  at  first  feel  that 
his  compound  microscope  will  never  afford  him  either 
amusement  or  instruction.  How  glaring  and  how  laugh- 
able will  such  a  mistake  appear  after  six  months'  use 
of  the  instrument !  When  recommending  a  friend  to 
purchase  a  microscope,  he  will  speak  of  that  conclusion 
as  an  amusing  episode  in  his  life.  Yet  the  beginner, 
especially  if  alone,  or  if  without  even  a  friend  to  sug- 
gest, or  an  experienced  microscopist  to  instruct,  must 
necessarily  be  somewhat  at  a  loss  as  to  how  to  make  a 
start,  and  I  know  of  no  remedy  for  this  unpleasant  feel- 
ing except  to  experiment.  Take  the  first  small  object 
that  may  be  convenient,  place  it  on  a  glass  slip,  and  ex- 
amine it  with  a  low-power  objective ;  add  a  drop  of  wa- 
ter, cover  it  with  a  thin  glass  square,  and  note  the  change 
in  its  appearance.  But  do  not  imitate  the  man  who  re- 
turned his  microscope  to  the  manufacturer  because,  as 
he  said,  it  would  not  show  the  crystals  in  sugar.  After 
much  questioning  it  was  discovered  that  he  had  placed  a 
huge  lump  of  loaf-sugar  on  the  stage,  expecting  that  the 
crystals  would  at  once  be  conspicuous.  And  do  not  imi- 
tate the  man  who  put  on  his  stage  a  piece  of  anthracite 
coal  direct  from  the  bin,  expecting  it  to  reveal  its  vegeta- 
ble nature  and  fern  fragments  or  impressions  without 
any  previous  preparation.  A  lump  of  sugar  or  of  coal 
is  a  dark  object  when  an  attempt  is  made  to  throw  light 
through  it  by  a  microscope  mirror,  yet  both  are  beau- 
tiful ami  interesting  when  viewed  as  opaque  objects, 
with  the  light  reflected  on  them  from  the  mirror  swung 
13 


276  MICEOSCOPY  FOR  BEGINNERS. 

above  the  stage.  To  see  the  sugar  crystals,  however,  or 
the  structure  of  coal,  demands  some  careful  and  skil- 
ful preliminary  preparation  of  the  materials.  The  coal 
must  be  sliced  and  ground  down  until  it  becomes  trans- 
parent, or  at  least  translucent,  an  operation  that  needs 
an  expert  to  accomplish.  Sugar  crystals  can  be  seen  by 
any  one,  as  the  reader  will  presently  learn. 

The  smaller  the  object  the  better  it  usually  is  for  mi- 
croscopic examination.  The  field  of  even  a  low-power 
objective  is  much  smaller,  and  consequently  includes 
less  of  the  object  than  the  beginner  would  imagine. 
Try  the  experiment  by  placing  a  piece  of  hair  a  quarter 
of  an  inch  long  under  the  one-inch  objective.  You  will 
not  be  able  to  see  both  ends  of  the  hair  in  the  field  at 
the  same  time.  The  stage  must  be  moved  for  what  ap- 
pears to  be  a  long  distance  before  the  end  is  brought 
into  view.  With  the  one-fifth  objective  the  field  is  still 
smaller,  and  the  higher  the  power  the  smaller  the  field. 

The  object  should  also  be  as  thin  as  possible,  so  that 
the  light  may  pass  through  it,  unless  it  is  to  be  viewed 
as  an  opaque  object,  with  the  light  thrown  on  it  from 
the  mirror  above  the  stage.  In  that  case  the  thickness 
makes  but  little  difference,  if  the  beginner  will  remem- 
ber that  the  microscope  is  for  the  study  of  small  things. 
In  opaque  objects,  however,  only  the  surface  can  be  ex- 
amined— an  important  and  often  a  beautiful  part — but 
in  transparent  substances  the  internal  structure  can  be 
seen. 

The  following  is  a  short  list  of  common  objects  of  in- 


COMMON  OBJECTS  WORTH  EXAMINING.  277 

terest  to  the  beginner,  and,  indeed,  to  any  one.  They 
are  all  very  accessible  in  the  writer's  locality ;  it  is 
hoped  that  they  are  equally  accessible  to  the  reader. 
The  list  is  intended  only  as  a  start,  or  a  hint  as  to  what 
may  be  examined,  and  be  interesting  yet  common  and 
abundant.  The  beginner  will  soon  cease  to  be  a  begin- 
ner. He  will  before  long  become  so  interested  in  some 
special  class  of  nature's  handiwork  that  he  will  leave 
all  the  others  and  devote  himself  to  that  one.  No  sin- 
gle student  can  expect  or  hope  to  cultivate  all  depart- 
ments of  microscopical  science.  The  field  is  too  vast 
and  life  is  too  short.  Most  heartily  would  I  recom- 
mend the  beginner  in  the  use  of  the  microscope  to 
spend  several  years,  if  necessary,  in  taking  short  excur- 
sions into  as  many  different  microscopical  departments 
as  possible,  and  to  then  intelligently  make  a  selection  of 
some  one  scientific  field,  of  which  there  are  many,  and 
make  its  cultivation  the  work  and  the  recreation  of  his 
leisure  hours.  The  work  will  soon  become  recreation, 
and  the  recreation  will  soon  result  in  increased  knowl- 
edge not  only  to  the  student-worker  but  to  the  scientific 
world  at  large.  There  can  be  no  better  way  of  employ- 
ing one's  leisure  hours  than  by  scientific  work  or  even 
by  scientific  play.  The  illustrious  Leidy,  one  of  the 
greatest  of  living  naturalists  and  investigators,  says  in 
his  monograph  on  the  fresh-water  Khizopods  of  North 
America,  "The  study  of  natural  history  in  the  leisure 
of  my  life,  since  I  was  fourteen  years  of  age,  has  been 
to  me  a  constant  source  of  happiness,  and  my  experience 


278  MICROSCOPY  FOR  BEGINNERS. 

of  it  is  such  that,  independently  of  its  higher  merits,  I 
warmly  recommend  it  as  a  pastime,  than  which,  I  be- 
lieve, no  other  can  excel  it.  At  the  same  time,  in  ob- 
serving the  modes  of  life  of  those  around  me,  it  has 
been  a  matter  of  increasing  regret  that  so  few,  so  very 
few,  people  give  attention  to  intellectual  pursuits  of  any 
kind.  In  the  incessant  and  necessary  struggle  for  bread, 
we  repeatedly  hear  the  expression  that  '  man  shall  not 
live  by  bread  alone,'  and  yet  it  remains  unappreciated 
by  the  mass  of  even  so-called  enlightened  humanity. 
In  common  with  all  other  animals,  the  engrossing  care 
of  man  is  food  for  the  stomach,  while  intellectual  food 
remains  unknown,  is  disregarded  or  rejected." 

1.  SCALES  FEOM  INSECTS'  WINGS. — Butterflies'  wings 
are  profusely  covered  by  minute  scales  of  great  beauty 
of  form  and  color.  They  differ  widely  in  different 
kinds  of  butterflies,  and  often  on  different  parts  of  the 
same  wing.  Gnats  and  mosquitoes  are  also  a  source  of 
supply  for  still  more  minute  and  curious  scales.  To 
obtain  them  from  the  butterfly,  brush  the  wing  with  a 
small  camel's -hair  pencil,  or  gently  scrape  it  with  the 
point  of  a  penknife,  and  examine  the  fine  dust  that 
falls.  Gnats  and  mosquitoes  may  be  allowed  to  fly 
about  in  a  small,  perfectly  dry  phial,  and  the  scales  thus 
knocked  off  are  to  be  transferred  to  the  slip  by  invert- 
ing the  bottle  and  tapping  it  against  the  glass.  The 
more  mosquitoes  imprisoned,  of  course  the  more  numer- 
ous will  be  the  scales.  The  common  clothes -moth  is 


COMMON  OBJECTS  WORTH  EXAMINING.  279 

also  a  scale-bearer.  The  abundant  Lepisma  saccharina, 
a  little,  flattened,  fish-shaped,  silvery  creature,  often  seen 
running  about  old  books,  is  covered  with  scales  which 
were  at  one  time  used  as  test  objects.  They  may  be 
obtained  by  tapping  the  animal  against  a  slide,  or  by 
scraping  the  surface  gently.  All  scales  may  be  exam- 
ined and  mounted  dry.  A  small  piece  cut  from  the 
wing  of  a  butterfly  and  viewed  as  an  opaque  object, 
will  show  the  arrangement  of  the  scale-like  feathers,  a 
sight  well  worth  seeing. 

2.  ELYTRA. — The  hard  wing-covers  (elytra}  of  beetles 
are  often  of  startling  beauty  when  examined  with  a 
strong  light  as  opaque  objects.     They  are  not  transpar- 
ent, and  cannot  be  made  so,  consequently  only  the  sur- 
face can  be  viewed.     They  are  to  be  examined  and 
mounted  dry. 

3.  INSECTS'  FEET  vary  greatly  in  appearance  and  struct- 
ure.    They  afford  an  endless  supply  of  the  most  inter- 
esting objects.     They  should  be  cut  off  with  sharp  scis- 
sors, so  as  to  include  part  of  the  leg,  and  examined  in 
water.     If  the  air  clings  to  the  bristles  on  the  leg,  dip 
the  latter  into  a  drop  of  alcohol  and  transfer  it  to  the 
water  on  the  slide  before  the  alcohol  evaporates.     The 
feet  of  the  two  or  three  kinds  of  flies  that  frequent  our 
houses,  the  feet   of  spiders   and  those  of  caterpillars, 
should  not  be  overlooked  by  the  beginner.     Spiders  can 
be  obtained  at  all  seasons,  even  in  the  winter,  by  search- 
ing the  dark  corners  of  the  cellar  where  the  furnace  is. 

4.  EYES  OF  INSECTS  should  be  viewed  as  opaque  ob- 


280  MICROSCOPY  FOR  BEGINNERS. 

jects,  unless  the  student  is  sufficiently  expert  to  be  able 
to  remove  the  pigment  matter  and  so  make  them  trans- 
parent. This  can  be  done  with  moderate  ease  in  the 
large  compound  eyes  of  the  house-fly,  but  with  most 
other  insects  it  is  a  delicate  operation.  The  eyes  are  re- 
moved with  sharp  scissors,  soaked  in  solution  of  caustic 
potash,  and  the  pigment  washed  from  the  inside,  if  nec- 
essary, with  a  fine  wet  camel's-hair  brush.  The  work  is 
best  done  under  water,  and  the  cleaned  eye  may  then  be 
examined  in  water.  The  compound  eyes  of  insects  like 
the  house-fly  are  usually  so  large  and  convex  that  only  a 
small  part  of  the  surface  can  be  brought  into  focus  at 
the  same  time ;  they  are  often  sufficiently  transparent 
to  be  quite  easily  studied  without  the  troublesome 
cleaning  process.  The  facets  of  compound  eyes  often 
have  long  hairs  between  them.  The  eyes  of  spiders  are 
several,  and  are  arranged  on  the  top  of  the  head.  If  the 
spider  is  small,  place  the  whole  body  under  a  low  power, 
and  view  as  an  opaque  object ;  otherwise  cut  into  parts 
to  suit.  The  eyes  have  a  wicked  look  as  they  brightly 
gleam  in  the  reflected  light. 

5.  PKOBOSCES  OF  INSECTS  are  as  numerous  and  varied  in 
structure  as  the  insects.  They  should  be  cut  off  close  to 
the  body,  squeezing  the  insect  to  force  out  the  parts  if 
necessary.  Examine  in  water  or  glycerine,  covering  them 
with  a  thin  glass  square  or  circle  as  already  explained. 
The  tongue  or  proboscis  of  a  butterfly  is  interesting. 
The  latter  is  usually  quite  visible  as  a  small  coil  just 
under  the  front  of  the  head.  It  may  be  unrolled  with 


COMMON  OBJECTS  WORTH  EXAMINING.  281 

a  needle,  and  then  cut  off  close  to  its  point  of  attach- 
ment. It  is  composed  of  two  longitudinal  parts  which 
separate  easily.  Examine  in  water  or  Canada  balsam, 
and  notice  the  one  or  more  rows  of  little  projections 
forming  conspicuous  barrel-shaped  objects  on  the  tip  of 
some  butterflies'  tongues.  These  are  supposed  to  be 
either  papillae  of  taste  or  implements  with  which  to 
tear  open  the  nectar  glands  within  the  flower. 

6.  EGGS  OF  INSECTS  cannot  always  be  obtained  when 
wanted,  but  they  make  beautiful  objects.  They  should 
be  viewed  as  opaque  bodies,  unless  they  are  found  after 
the  larva  has  escaped,  when  they  may  be  transparent 
and  can  be  examined  in  water.  The  surface  markings 
are  in  a  great  variety  of  patterns. 

T.  INSECTS,  if  small,  are  to  be  examined  alive  and  as 
opaque  objects.  They  may  be  imprisoned  in  a  deep 
cell  with  a  thin  cover  above  them.  If  the  cover  tends 
to  slide  off  when  the  microscope  is  inclined,  allow  a  very 
small  drop  of  water  to  run  under  one  corner ;  the  capil- 
lary attraction  will  then  hold  it  in  place.  The  quantity 
of  water  must  not  be  sufficient  to  extend  into  the  cell. 
If  the  insect  is  very  small  it  may  be  killed  by  an  im- 
mersion in  a  very  strong  solution  of  carbolic  acid,  and 
then  transferred  to  Canada  balsam,  as  described  in  the 
books  devoted  to  microscopical  mounting.  This  treat- 
ment often  renders  the  body  beautifully  transparent, 
forcing  out  the  probosces  and  spreading  the  legs  in  a 
very  satisfactory  manner. 

8.  GIZZAEDS.— Pull  off  the  head  of  a  common  cricket 


282  MICROSCOPY  FOR  BEGINNERS. 

or  katydid,  and  the  gizzard  will  usually  be  obtained  as 
an  oblong,  hard,  reddish  -  brown  enlargement  attached 
between  the  oesophagus  and  the  upper  part  of  the  ali- 
mentary tube  below  the  larger  food-sack.  Free  it  from 
these,  cut  it  open  lengthwise,  and  wash  the  interior  with 
a  camel's-hair  brush.  View  it  as  a  transparent  object. 
The  grinding-teeth  are  well  worth  studying.  The  giz- 
zards of  some  beetles  are  also  interesting.  They,  how- 
ever, are  to  be  dissected  out  with  fine  scissors  and  nee- 
dles. The  work  is  best  done  under  water. 

9.  SCALES  OF  FISH  are  obtainable  in  great  variety,  and 
make  beautiful  objects  for  low  powers.     They  are  often 
coated  with  a  tenacious  mucous  material  which  may  be 
removed  by  washing  in  a  solution  of  caustic  potassa. 
They  should  be  examined  in  water  or  glycerine. 

10.  HAIK. — The  hair  of  animals,  from   the  human 
animal  down  to  the  insects,  forms  an  important  class  of 
objects  for  study.     Every  animal  has  characteristic  hair 
that  may  be  recognized  if  the  observer  have  sufficient 
skill  in  the  use  of  the  microscope  and  sufficient  knowl- 
edge of  the  subject ;  but  to  attempt  to  identify  hair  de- 
mands careful  work  with  high  powers.     It  cannot  be 
done  with  a  pocket-lens,  nor  with  a  one-inch  objective, 
unless  the  specimen  is  extremely  common,  and  the  ob- 
server has  examined  it  often  and  attentively.     The  dif- 
ficulty is  increased  by  the  fact  that  the  hair  of  our  small 
mammals  differs  greatly  in  microscopic  structure  in  dif- 
ferent parts  of  the  body.     I  once  heard  a  lecturer  claim 
to  have  identified  an  unknown  sample  of  hair  with  a 


COMMON   OBJECTS  WORTH  EXAMINING.  283 

Coddington  lens,  a  claim  that  lie  would  have  hesitated 
to  make  if  he  had  known  anything  about  the  subject. 
A  single  fibre  of  hair  can  be  recognized  as  such,  and  can 
be  very  readily  distinguished  from  a  fibre  of  wool,  silk, 
or  cotton,  all  of  which  the  beginner  should  examine, 
since  they  will  very  often  be  found  on  the  slide  and 
may  be  mistaken.  Hair  is  easily  accessible  on  the  cat, 
mouse,  horse,  and  other  animals.  It  should  be  examined 
in  water  with  a  high  power.  The  hair  of  the  mouse  is 
very  peculiar,  as  is  also  that  of  most  bats.  Colored 
fibres  of  wool  are  often  seen  on  a  slide,  having  dropped 
there  from  the  observer's  clothing  or  floated  from  the 
carpet.  They  must  not  be  mistaken  for  a  remarkable 
class  of  worms. 

11.  HAIRS  OF  ANTHKENUS  LAKVA. — The  "  buffalo  bee- 
tle "  (Anthrenus  scrophuldrice,  and  its  relative,  A.  mu- 
seorum)  are  pests  that  are  becoming  much  too  common 
in  our  houses.     The  larvae,  however,  can  be  utilized  by 
the  microscopist  as  a  supply  for  hairs  of  great  interest. 
The  red  dish -brown  tufts  on  the  various  parts  of  the 
body,  especially  of  Anthrenus  museorum,  are  composed 
of  hairs  having  a  remarkable  structure,  which  the  begin- 
ner is  advised  to  examine  for  himself,  especially  since 
words  cannot  adequately  describe  it.     The  hairs  should 
be  studied  in  water  or  Canada  balsam. 

12.  LINGUAL  RIBBONS  or  MOLLUSKS. — The  tongue,  pal- 
ate, lingual  ribbon,  or  odontophore  (it  has  received  sev- 
eral names)  is  the  organ  by  which  the  water-snails  rasp 
off  their  food  from  submerged  stones  and  plants.     It  is 

13* 


284  MICROSCOPY  FOR  BEGINNERS. 

a  band- like  body  having  many  rows  of  short,  variously 
formed  teeth,  which,  under  the  microscope,  present  a 
beautiful  and  dazzling  appearance.  It  is  situated  so 
that  it  may  be  partially  protruded  and  used  as  a  file, 
which  not  only  removes  the  food  particles,  but  carries 
them  into  the  mouth.  It  may  be  obtained  from  any 
of  the  pond-snails,  either  by  dissecting  it  out  under  the 
microscope  with  needles — a  tedious  process,  successful 
in  the  hands  of  advanced  workers — or  by  dissolving  the 
soft  parts  of  the  snail  by  boiling  the  animal  in  a  solution 
of  caustic  potassa.  Drop  the  snail  into  a  test-tube  con- 
taining a  small  quantity  of  the  solution,  and  boil  until 
all  of  the  soft  body  has  disappeared.  "When  cold  pour 
off  the  liquid  very  gently,  and  the  lingual  ribbon  will 
be  found  at  the  bottom  usually  without  trouble,  although 
it  is  often  small  and  always  perfectly  transparent.  The 
last  few  drops  may  be  poured  on  a  slip  and  examined 
with  a  low  power,  when  the  lingual  ribbon  will  be  seen 
and  can  be  isolated  with  a  needle.  The  form,  size,  and 
arrangement  of  the  teeth  vary  greatly  in  the  different 
water-snails.  To  see  them  is  worth  all  the  trouble  that 
their  preparation  seems  to  demand.  The  ribbons  should 
be  examined  in  water  or  glycerine.  A  high  power  will 
often  be  required  to  show  the  teeth  well. 

13.  The  delicate  epidermis  from  the  leaves  of  plants 
can  be  obtained  at  any  time  in  an  unlimited  supply  and 
variety — in  summer  from  the  wild  plants,  in  winter  from 
those  cultivated  in  the  house.  The  cells  forming  this 
thin  and  usually  colorless  membrane  vary  in  form  and 


COMMON  OBJECTS  WORTH  EXAMINING.  285 

size  in  the  leaves  of  every  plant,-  and  the  stomata  or 
breathing  pores  also  present  very  varied  shapes,  being 
most  abundant  on  the  under  surface.  The  cells  are  usu- 
ally empty ;  occasionally,  however,  they  contain  some 
chlorophyl  grains  and  sometimes  diffused  coloring  mat- 
ter. The  cuticle  can  be  sliced  off  with  a  sharp  razor, 
but  a  better  way  is  to  strip  it  off  by  tearing  the  leaf  in 
a  manner  easily  acquired  but  hardly  describable.  The 
piece  obtained  may  be  very  small,  but  it  will  probably 
be  sufficient  for  examination.  All  cuticles  should  be 
examined  in  water. 

14:.  DEUTZIA  SCABRA,  a  handsome  shrub  now  very 
common  in  cultivation,  has  leaves  of  special  interest  on 
account  of  the  beautiful  stellate  hairs  studding  the  sur- 
face. The  cuticle  may  be  removed  and  viewed  as  a 
transparent  object,  or  a  portion  of  the  leaf  may  be  ex- 
amined by  reflected  light.  By  either  method  the  ob- 
server will  be  pleased  and  interested.  These  stellate 
hairs  are  hard,  brittle,  and  glass-like,  and  they  are  occa- 
sionally so  well  developed  that  they  are  visible  to  the 
naked  eye  as  minute  glistening  stars.  Under  a  good 
pocket-lens  they  are  at  all  times  apparent.  They  are 
most  abundant  on  the  upper  surface. 

15.  OLEANDER  LEAVES  (Nerium  Oleander,  a  shrub 
frequently  cultivated)  have  large  stomata,  which  contain 
beneath  the  general  surface  of  the  leaf,  but  often  pro- 
jecting from  the  aperture  of  the  breathing-pore,  many 
short,  variously  curved  hairs.  To  observe  them,  cut 
with  a  sharp  razor  a  very  thin  slice  across  the  leaf, 


286  MICROSCOPY  FOR  BEGINNERS. 

and  examine  the  section  in  water,  decolorizing  and 
staining  it,  if  desired,  by  some  of  the  many  processes 
described  in  the  books  devoted  to  microscopical  mount- 
ing. The  leaves  also  contain  numerous  crystals  in  the 
form  called  sphaeraphides,  a  sphere  of  crystal  roughened 
by  minute  points  projecting  from  all  parts  of  the  sur- 
face. 

16.  PLANT  HAIRS  are  as  inexhaustible  in  appearance 
and  structure  as  are  animal  hairs.     They  are  formed  of 
cells  of  varied  size,  shape,  and  contents.     In  many  a 
circulation  of  the  protoplasm  or  cyclosis  may  be  noticed. 
They  are  simple  or  branched,  terminating  in  a  long 
point,  a  blunt  apex,  or  in  a  spherical  or  other  shaped 
gland.     They  may  be  examined  by  stripping  off  the 
cuticle  and  studying  it  as  a  transparent  object  in  water. 
If  the  air  adheres  to  the  hairs  and  obscures  them,  as 
often  happens  to  the  very  abundant  branching  hairs  of 
the  common  mullein  ( Verbdscum ),  dip  the  cuticle  in  a 
drop  of  alcohol,  and  immediately  transfer  it  to  the  drop 
of  water  already  prepared  on  the  slide.     Hairs  are  to 
be  found  on  some  part  of  almost  every  plant. 

17.  POLLEN  from  the  anthers  of  blooming  flowers  is 
one   of   the   most  attractive  of  very  common  objects 
which  the  beginner  can  find  for  examination  as  a  dry 
mount.     It  can  be  obtained  by  simply  tapping  the  slide 
with  the  ripe  anther,  when  the  pollen  will  be  visible  to 
the  naked  eye  as  a  yellow  dust,  resolvable  by  the  micro- 
scope into  golden  grains  of  varied  forms  and  often  of 
remarkable  surface  sculpturing.     It,  of  course,  differs  in 


COMMON  OBJECTS  WORTH  EXAMINING.  287 

shape,  size,  and  appearance  in  different  plants.  The 
supply  of  new  forms  is  therefore  almost  unlimited.  In 
some  the  yellow  dust  consists  of  ovate  grains  with  a 
central  longitudinal  depression,  like  a  grain  of  wheat ;  in 
others  it  is  triangular  or  spherical ;  in  most  it  is  delicately 
roughened  or  attractively  marked.  The  pollen  of  the 
Passion-flower,  the  hollyhock,  and  the  dandelion  are  es- 
pecially noteworthy.  The  study  of  pollen  and  the  draw- 
ing of  the  magnified  image  should  be  particularly  pleas- 
ant work  for  ladies.  The  botanical  study  necessary  to 
identify  the  plant  supplying  the  pollen  is  advantageous 
and  agreeable.  The  delicate  microscopical  work  needed 
is  more  than  pleasant,  and  is  suited  to  the  refined  tastes 
of  the  ladies.  The  use  of  a  pencil  to  record  and  pre- 
serve the  beautiful  forms  and  their  markings  will  add 
much  to  the  enjoyment  and  the  profit ;  the  work  will 
then  be  both  attractive  and  inspiring. 

18.  SEEDS  of  wild  plants  form  another  almost  inex- 
haustible group,  some  of  them  being  exquisite  beyond 
description.  Even  so  common  and  so  lowly  a  plant  as 
the  carrot  has  seeds  of  very  peculiar  appearance.  The 
poppy,  the  cardinal  flower  (Lobelia  cardindlis),  and  oth- 
er lobelias,  are  among  the  many  worth  noting.  The 
portulaca  and  the  many  wild  geraniums  are  also  desir- 
able. They  should  be  examined  dry  as  opaque  objects. 
The  seeds  of  Collomia  have  long  been  favorites  on  ac- 
count of  the  peculiar  spiral  vessels  on  their  surface. 
The  plant  is  a  subtropical  one,  and,  so  far  as  I  know, 
does  not  grow  uncultivated  in  any  part  of  our  country. 


288  MICROSCOPY  FOR  BEGINNERS. 

The  seeds,  however,  are  usually  on  sale  by  the  micro- 
scopical dealers.  To  see  the  spirals,  cut  off  a  small 
piece  of  the  outer  coating  of  the  seed,  place  it  in  a  shal- 
low cell  with  a  thin  cover  above  it.  Arrange  the  slide 
on  the  stage,  focus  the  objective,  and  while  looking 
through  the  instrument  allow  a  drop  of  water  to  run 
into  the  cell  and  around  the  object.  Immediately  the 
spiral  vessels  will  seem  to  be  springing  and  growing  out 
of  the  seed  in  a  remarkable  way.  They  are  adherent  by 
means  of  a  mucilaginous  substance,  soluble  in  water,  and 
at  the  touch  of  the  drop  which  dissolves  their  bonds 
they  are  set  free,  to  the  astonishment  of  the  observer 
who  sees  them  for  the  first  time. 

19.  EQUISETUM  SPORES  (Equisetum  arvense)  are  worth 
collecting  and  examining  as  transparent  dry  objects. 
The  plant  is  often  called  "  Horse  -  tail "  or  "  Scouring- 
rush,"  and  is  to  be  found  almost  everywhere  in  sterile 
places,  especially  along  the  railroad.  The  spores  are 
small,  almost  spherical,  and  have  four  long  narrow  fila- 
ments which,  when  moistened,  curl  and  curve  arid  twist, 
and  toss  the  spores  about  in  every  direction  by  what 
has  been  styled  a  "  quadrupedal  hornpipe."  If  a  quan- 
tity of  them  is  placed  on  a  slide  and  gently  breathed 
upon,  the  moisture  of  the  breath  will  set  those  four  long 
threads  into  motion,  and  the  dance  will  at  once  begin. 
One  of  my  friends  makes  a  permanent  mount  of  these 
curious  spores  by  forming  a  cell  of  a  single  strand  of 
gold -lace  fringe,  and  of  course  covering  them  with  a 
thin  glass,  fastened  on  with  shellac  cement,  but  so  as  not 


COMMON  OBJECTS  WORTH  EXAMINING.  289 

to  close  the  little  apertures  between  the  fibres  of  the 
gold  lace.  By  breathing  through  these  little  openings 
the  moisture  will  at  any  time  start  the  spores  on  their 
"quadrupedal  hornpipe,"  and  when  they  are  dry  the 
performance  may  be  repeated.  An  ordinary  cell  with 
the  cement  ring  cut  into  narrow  parts  by  the  strokes  of 
a  penknife,  so  that  the  moisture  could  enter,  would  prob- 
ably answer  the  purpose  as  well  as  my  friend's  more 
elaborate  contrivance. 

20.  PLANT  CRYSTALS,  already  referred  to  (No.  15),  are 
found  in  the  tissues  of  many  plants.  They  occur  in 
four  different  and  easily  recognizable  forms  as  follows : 

a.  Raphides. —  Small  needle-like  crystals,  with  long 
shafts  very  gradually  tapering  to  the  pointed  ends. 
They  are  usually  found  collected  together  in  loose  bun- 
dles, and  generally  within  a  distinct  cell.  They  are 
abundant  in  Lemna,  in  common  Spiderwort  (Trades- 
cdntia),  Touch-me-not  (Impdtiens  falva),  the  Primrose 
(O£nothera\  the  Golden -club  (Orontium  aqudticum), 
Virginia  creeper  (Ampdopsis  quinquefolia),  and  many 
others. 

1}.  Sphcerdpkides. —  More  or  less  spherical  forms, 
smooth,  or  with  the  entire  surface  roughened  by  crystal- 
line projections.  They  usually  occur  within  a  distinct 
cell,  and  are  to  be  found  in  the  Oleander  (Nerium),  Ge- 
ranium, Oxalic,  Bouncing  Bet  (Sapondria  officindlis), 
Fleabane  (Erigerori),  Portulaca,  Hibiscus,  common  mal- 
low (Mdlva  rotundifolia\  and  others.  Yery  remarka- 
ble crystals  are  found  in  the  epidermal  cells  of  the  stem 


290  MICROSCOPY  FOR  BEGIXNERS. 

of  the  common  Rich  weed  (Pilea  pumila\  a  semitrans- 
parent  plant  growing  in  moist,  shady  places. 

c.  Long  Crystal  Prisms. — These  are  long  crystals, 
with  angular,  prismatic  shafts  and  angular  tips.     They 
never  occur  loosely  as  do  Raphides,  but  one  or  two 
together  in  the  tissue  of  the  plant.     They  are  abundant 
in  the  cultivated  Gladiolus,  Flower-de-luce  (Iris  versi- 
color),  some  of  the  Asters,  Cynthia  Virginica,  Hawk- 
weed  (Hierdcium),  the  Thistles  (Cirsium\  and  others. 

d.  Short  Crystal  Prisms. — These  are  cubical  crystals, 
long  or  short  squares  or  prisms,  indeed  all  those  forms 
which  cannot  be  classed  in  the  other  divisions.     They 
are  usually  found  in  distinct  cells,  and  often  also  in  ex- 
tensive rows  or  chains  along  the  veins  of  leaves,  espe- 
cially in  the  Leguminosse.     They  are  abundant  in  the 
Maple,  Linden,  white  and  red  clover  (Trifolium  repens, 
T.  pratense),  Onion,  Monkey-flower  (Mimulus  ringens), 
Rabbit's-foot  (Trifolium  arvense),  and  many  other  con> 
mon  plants. 

When  searching  for  these  crystals  a  small  fragment  of 
the  plant  should  be  crushed  with  a  penknife,  and  exam- 
ined in  water  with  a  moderately  high  power,  as  most 
of  the  crystals  are  small.  The  cuticle  should  also  be 
stripped  off.  This  may  be  done  in  the  onion  bulb  and 
Richweed  (P'dea). 

21.  CRYSTALS. — If  the  student  has  a  polariscope  he 
will  especially  appreciate  the  beauty  of  crystals  as  ex- 
emplified in  color ;  if  he  has  none  he  can  study  and  ad- 
mire the  beauty  of  their  forms.  Almost  any  soluble  salt 


COMMON  OBJECTS  WORTH  EXAMINING.  291 

may  be  made  to  crystallize  by  preparing  a  strong  solu- 
tion and  allowing  it  to  slowly  evaporate,  and  the  forma- 
tion of  the  crystals  may  be  watched  with  the  micro- 
scope. A  small  drop  is  placed  on  the  slip  and  allowed 
to  evaporate  while  on  the  stage.  Sugar  crystals  can  be 
prepared  in  this  way.  Common  salt  is  very  easily  made 
to  crystallize,  and  scarcely  anything  can  be  more  beau- 
tiful than  salt  crystals  viewed  as  opaque  objects  with  a 
strong  light  reflected  on  and  from  them.  The  follow- 
ing are  also  noteworthy  :* 

Tartaric  Acid. — Make  a  strong  solution  and  place  a 
large  drop  on  the  slide.  Evaporate  with  a  gentle  heat 
by  holding  the  slide  several  inches  above  the  top  of  the 
lamp  chimney. 

Gallic  Acid.— A.  small  drop  of  a  strong  solution  in  al- 
cohol should  be  allowed  to  evaporate  very  slowly. 

Pyrogallic  Acid. — A  strong  cold  solution  in  water 
forms  long  needle-shaped  crystals,  "  but  if  a  very  minute 
shower  of  some  insoluble  foreign  substance  be  allowed 
to  fall  upon  the  solution  when  on  the  slide  the  effect  is 
grand  —  each  minute  speck  forming  a  nucleus  around 
which  the  needle-shaped  crystals  gather,  forming,  if  ex- 
amined with  a  selenite  slide,  so  resplendent  an  object 
that  no  words  of  mine  can  adequately  describe  it."  * 

Chlorate  of  Potash. — Make  a  strong  solution  in  hot 
water  and  allow  a  small  drop  to  spread  evenly  over  the 
cell  and  evaporate  slowly.  To  form  dendritic  or  tree- 

*  American  Monthly  Microscopical  Journal,  August,  1883. 


292  MICROSCOPY  FOK  BEGINNERS. 

like  crystals  of  this  salt,  heat  a  drop  over  the  lamp.  As 
soon  as  the  crystals  begin  to  form  at  any  point,  tilt  the 
slide  so  that  the  liquor  may  ran  off,  then  continue  the 
crystallization  by  gentle  warmth. 

There  are  many  other  salts  which  produce  beautiful 
crystals  when  treated  in  the  above  or  a  similar  manner, 
but  the  student  would  doubtless  prefer  to  experiment 
for  himself,  rather  than  to  have  a  bare  list  set  down  be- 
fore him.  And  there  are  innumerable  other  common 
objects  easily  to  be  procured  and  worthy  of  study.  It 
is  not  possible  to  enumerate  a  millionth  part  of  them. 
Examine  for  yourself.  Try  and  see  what  a  good  thing 
a  microscope  is.  And  the  writer  wishes  the  reader  ev- 
ery success  in  the  use  of  the  delightful  instrument. 


GLOSSARY. 


Acute :  sharp  or  pointed. 

Alimentary :  pertaining  to  food. 

Antenna  (plural  antenna) :  a  jointed,  movable  tentacle  or  feeler  on 

the  head  of  certain  Crustacea  and  insects. 
Anterior :  front,  going  before. 
Aquatic :  living  or  growing  in  water. 
Assimilated:  turned  to  its  own  substance  by  digestion. 

Beak :  the  lengthened  end  or  front. 

Bi:  in  compound  words,  meaning  two. 

Bifid:  two-parted. 

Bosses :  knobs,  protuberances,  usually  rounded. 

Branchial :  relating  to  gills  or  branchiae. 

Carapace :  the  firm  shell  of  some  Infusoria,  Rotifers,  etc. 

Carnivorous :  flesh-eating. 

Caudal :  pertaining  to  the  tail. 

Cellular :  formed  of  or  possessing  cells. 

Chlorophyl :  the  green  coloring  matter  of  plants. 

Cilium  (plural  cilia) :  a  short,  fine,  vibrating  hair. 

Caecum  (plural  caeca) :  a  part  of  the  intestinal  tube. 

Colony :  a  cluster  of  several  or  many. 

Comminution:  the  act  of  pulverizing  or  grinding. 

Component :  composing  ;  an  elementary  part. 

Concave :  hollow  like  a  bowl. 

Conical :  cone-shaped. 

Conjunction :  union,  association. 

Constricted:  suddenly  narrowed  or  contracted. 

Contractile :  capable  of  being  shortened  or  drawn  together. 

Cordate :  heart-shaped. 


294:  GLOSSARY. 

Cornea :  the  transparent  membrane  forming  the  front  of  the  eye. 

Corpuscles :  particles  of  matter. 

Crenate :  scalloped,  or  with  rounded  teeth. 

Crescent :  shaped  like  the  new  moon. 

Crystalline :  resembling  crystal ;  clear  ;  transparent. 

Cuticle :  the  thin  membrane  covering  the  surface  of  plants  ;  the 

outermost  layer  of  the  skin. 

Cyclosis :  the  movement  of  protoplasm  within  a  closed  cell. 
Cylindrical :  like  a  cylinder  or  long,  circular  body. 

Dentate:  toothed.    . 

Denticulate :  with  small,  pointed  teeth. 

Diagonal :  extending  obliquely. 

Diffused :  spread  out,  extended. 

Disintegrated :  reduced  to  minute  parts. 

Distal :  the  furthest  part. 

Diverging :  spreading  from  a  central  point. 

Dorsal :  pertaining  to  the  back. 

Dorsum :  the  back. 


Ejected:  thrown  out. 

Elliptical:  oval. 

Emarginate :  notched. 

Epithelium :  the  membrane  lining  various  internal  cavities  and  free 

surfaces  of  animals. 

Expansile :  capable  of  being  expanded  or  widened. 
Extensile :  capable  of  being  lengthened  or  extended. 

Facet :  a  little  surface  or  face. 

Fascicle :  a  cluster. 

Filament :  a  thread,  or  resembling  a  thread. 

Fission :  division  or  cleaving. 

Flagellum  (plural  flagella) :  a  little  lash. 

Flexible :  capable  of  being  bent. 

Frond :  a  leaf  of  fern ;  the  entire  plant  of  Lemna. 

Frontal :  pertaining  to  the  front. 

Frustule :  the  entire  diatom,  consisting  of  two  valves  and  the  hoop. 

Furcate:  forked. 


GLOSSARY.  295 

Gelatinous :  like  jelly  or  gelatine. 

Globule :  a  small  round  particle. 

Granular :  formed  of  or  resembling  small  grains. 

Granules:  small  grains. 

Hemisplierical :  half  a  sphere. 
Hexagon :  a  figure  with  six  sides  and  angles. 
Hispid:  rough,  with  short,  stiff  hairs. 
Homogeneous :  of  the  same  kind  throughout. 
Hyaline :  glass-like,  transparent. 

Illoricate :  without  a  lorica. 

Imbricated :  overlapping  like  shingles  on  a  roof. 

Invested :  clothed,  covered. 

Labrum :  a  part  of  the  mouth  of  Crustacea  and  insects. 

Lanceolate :  lance-shaped. 

Larva  (plural  larvae) :  an  insect  in  its  first  stage  after  leaving  the  egg. 

Laterally :  by  the  sides. 

Lophopliore :  the  disk  supporting  the  tentacles  in  the  Polyzoa. 

Lorica,  (plural  loricoe) :  the  sheath  or  dwelling  of  certain  microscopic 

animals. 
Loricate :  with  a  lorica. 

Mastax :  the  internal  jaws  of  the  Rotifers. 
Median:  middle. 

Membranous :  formed  of  a  thin  skin. 
Moniliform :  like  a  string  of  beads. 
Monograph :  a  treatise  on  a  single  subject. 

Nodule :  a  small,  rounded  elevation. 

Oblong :  longer  than  broad. 

Obtuse:  blunt. 

(Esophagus:  the  tubular  passage  extending  from  the  pharynx  or 

throat  to  the  stomach. 
Opaque :  not  transparent. 
Ovoid :  egg-shaped  or  oval. 


296  GLOSSARY. 

Papilla  (plural  papittce) :  a  small  rounded  protuberance. 

Parasite :  a  hanger  on ;  as  one  animal  or  plant  living  at  the  expense 
of  another. 

Parietal:  pertaining  to  the  wall  or  side. 

Pellet:  a  little  ball  or  mass. 

Pellucid :  translucent  or  transparent. 

Pendent:  hanging. 

Perianth :  the  leaves  of  a  flower  that  cannot  be  distinguished  into  a 
calyx  and  corolla. 

Pigment :  coloring  matter. 

Podal :  pertaining  to,  or  used  as,  feet. 

Polyp :  a  radiate  animal,  without  locomotive  organs,  with  retractile 
tentacles  around  the  mouth,  and  a  hollow  body  in  which  are  sus- 
pended the  digestive  and  other  organs. 

Posterior :  the  rear  end. 

Prehensile :  adapted  for  grasping  or  seizing. 

Process :  a  part  prolonged  or  projecting  beyond  other  parts  connect- 
ed with  it. 

Protoplasm :  the  semi-fluid,  jelly-like  contents  of  cells. 

Protrusible :  capable  of  being  thrust  forward. 

Pulsating :  throbbing,  beating. 

Recurved :  directed  backward. 

Refracting :  bending  from  a  direct  course. 

Reticulated :  with  the  form  of  a  net. 

Retort :  a  chemical  glass  vessel. 

Retractile  :  capable  of  being  drawn  back  or  into  the  body. 

Rudimental :  imperfectly  developed  or  formed  ;  immature. 

Segment :  one  of  the  rings  or  component  parts  of  a  worm  or  other 

body. 

Semi:  in  compound  words,  meaning  half. 
Serrate :  toothed  like  a  saw. 
Shaft :  the  stem  or  straight  part  between  the  ends. 
Silicious  :  resembling  or  formed  of  silica. 
Spherical :  round  like  a  ball. 
Spinous :  bearing  spines. 
Spiral :  winding  like  a  screw. 
Spore:  the  minute  seed  of  flowerless  plants. 


GLOSSARY. 

Statoblast :  the  winter  egg  of  the  Polyzoa. 

Striated :  finely  streaked. 

Sub  :  in  compound  words,  meaning  under,  or  less  than. 

Submerged :  under  water. 

Saltation :  a  groove. 

Tortuous:  winding,  twisting. 
Translucent:  semitransparent. 
Truncate :  as  if  cut  off  square. 
Tubercle :  a  small,  knob-like  elevation. 
Tubular :  resembling  or  formed  of  a  tube. 

Utricle :  a  little  sack  or  bladder. 

Ventral:  pertaining  to  the  lower  surface;  opposed  to  dorsal. 
Ventrum:  the  concave  side  of  Closterium  (as  here  used). 
Viscera :  the  intestines,  or  abdominal  contents. 
Visor :  the  fore-piece  of  a  cap. 

Whorl :  several  leaves  in  a  circle  around  the  stem. 
Zoophyte :  a  word  applied  to  certain  plant-like  animals. 


INDEX. 


Acanthocystis,  1 1 5, 1 19. 

—  chcetopkora,  119. 
Adinopkrys,  116,  120. 

—  so/,  120. 
Actinonphrerium,  116,  121. 

—  Eichhornii,  121. 
Actlnurus.  207,  208,  211. 
Adapter,  12. 
Adjustment,  the  coarse,  18. 

—  the  fine,  20. 
jftolosoma,  164,  188,  194. 
Agassiz  Association,  the,  xi. 

—  Prof.  Louis,  205. 
Air-bubbles,  40.     • 

AlgEe,  fresh-water,  63,  64,  69,  72,  73, 

99, 102. 
Algae,  fresh-water,  key  to  genera  of, 

103. 

Algae,  fresh-water,  to  preserve,  88. 
Alonopsis,  246,  251. 
American     Monthly     Microscopical 

Journal,  161,  219,  291. 
Amceba,  111,  114-118. 

—  proteins,  117. 

—  radiosa,  118. 

—  villosa,  118. 

Ampetopsis    quinquefolia,    raphides 

in,  289. 

Amphileptus,  139,  151. 
Anabeena,  103,  105. 
Anacharis  Canad&isis,  58,  162. 

—. cyclosis  in,  59. 

Anguillula,  164, 166,  183. 

—  aceti,  184. 

—  glutinis,  184. 
Animalcule,  131. 

Animals,  microscopic,  to  collect,  45, 
47. 

H 


Anthrenus  larva,  hairs  of,  283. 

—  mitseorum,  283. 

—  scrophidarice,  283. 

Apgar,  Prof.  A.  C.,  oa  Bunsen-bum- 

er,  36. 
Arcella,  112, 116, 126, 127. 

—  dentata,  127. 

—  milrata-,  127. 

—  vulffarix,  127. 

Arm  of  microscope  stand,  10. 
Arrenurus,  261,  267,  270. 
Artcmia,  243,  247,  256. 
Arthrodesmus,  75,  87. 

—  convergens,  87. 

—  incus,  87. 
Astasia,  139,  149. 

Asters,  crystal  prisms  in,  290. 
Atax,  267,  271. 

Atwood,  H.  F.,  on  Brachionm,  219. 
Aulopfionts,  183, 193. 

B. 

Bacillaria,  93-95. 

—  paradoxa,  95. 
Bambusina,  74,  76. 

—  Brebissonii,  76. 
Batrachospermum,  103, 104. 

—  moniliforme,  104. 
Beetles,  gizzard  of,  282. 
Body  of  microscope  stand,  10. 
Books  to  assist  in  mounting  objects, 

46. 

JSosmina,  246,  248. 
Bottles  for  collecting,  45. 
Bouncing  Bet,  289. 
Brachionus,  208,  219. 

—  conium,  219 
Branchipw,  243,  247,  258. 
Breckenfeld,  A.  II.,  on  preserving 

Hydra,  161. 


300 


INDEX. 


Brewster,  Sir  David,  the  inventor  of 

the  Coddington  lens,  7. 
Bubbles,  air,  40. 
BulbocluEte,  104/1 10. 
Bull's-eye  condensing  lens,  23. 
Bunsen-burner,  Apgar's,  36. 

to  make,  37. 

Butterfly,  scales  from,  278,  279. 


C. 

Camera  lucida,  42. 
Camptocerais,  246,  250. 
Canada  balsam,  25. 
Canthocamptus,  241,  245,  246,  253. 
Carchesium,  138,  140. 
Cardinal  flower,  287. 
Carrot,  seeds  of,  287- 
Caterpillars,  feet  of,  279. 
Cells,  cement,  30,  31. 

—  device  for  centring,  31. 

—  paper,  32. 

—  plant,  59. 

Cement,  Brown's  rubber,  83. 

—  shellac,  30. 
Centropyxis,  116,  126. 

—  aculcata,  126. 
Ceratophyllum  demersum,  48,  55. 
Ceriodaphnia,  246,  249. 
Chcetogaster,  164,  188,  190. 
Cluetonotus,  163,  165-167. 

—  acaHt/iodes,  172, 177. 

—  acanlhophoms,  172, 179. 

—  caudal  appendages  and  glands, 
169. 

Cluctonotm,  classification  of,  170. 

—  concinnits,  171, 173. 

—  dorsal  appendages,  168. 

—  eggs  of,  170. 

—  enormis,  172,179. 

—  food  of,  168. 

—  head,  168. 

—  key  to  species  of,  171. 

—  larus,  171,  175. 

—  longispinosus,  172, 176. 

—  loricatus,  171, 173. 

—  mazimus,  171, 175. 

—  mouth  of,  168. 

—  octonarius,  172,  176. 

—  oesophagus  of,  1 69. 

—  podura,  171,172. 


CJuetonotus  rhomboidcs,  171, 172 

—  gpinifer,  172, 177. 

—  spinosuhis,  172,  176. 

—  sulcatus,  171, 173. 

—  to  collect,  168. 
Chcetophora,  104,  108,  167. 

—  elegcms,  108. 
Chilodon,  140,  154,  215. 

—  meffalotrochce,  215. 
C/iilomonas,  139, 149. 
Chirocephalus,  247,  257. 
Ckironomus,  eggs  of,  1 66. 

—  larva,  163,  165, 166. 
Chlorophyl,  59,  62. 
Chydorm,  246,  251. 
Cilia  of  Infusoria,  135. 

—  of  Turbellaria,  180. 
Circles,  thin  glass,  29. 
Cirsiwn,  crystal  prisms  in,  290. 
Clathrulina,  112, 116,  130. 

—  deffftns,  130. 
Closterium,  72-74,  77-80. 

—  acerosnm,  78. 

—  acuminatum,  79. 

—  Diana,  79. 

—  Ehrenbergii,  79. 

—  jnncidum,  78. 

—  key  to  species,  78. 

—  lineaium,  78. 

—  Lumda,  79. 

—  rostralum,  80. 

—  sctaceum,  80. 

—  Vemu,l9. 

Clover,  crystal  prisms  in,  290. 
Coal,  275. 
Cocconeis,  93,  97. 

—  pedicuhts,  97. 
Cocconema,  93,  96. 

—  lanceolata,  96. 
Coddington  lens,  7. 
Collecting-bottle,  45. 
Collomia,  seeds  of,  287. 
Condensing-lens,  bull's-eye,  23. 
Conjugation  of  Spiroffyra,  106. 
Copper  solution  for  preservin, 

raids  and  Algae,  88. 
Cosmariwn,  75,  84,  85. 

—  Hrebissonii,  85. 

—  mtuyarttiferwn,  85. 

—  pyramidatum,  85. 

—  SalfsU,  85. 


IXDEX. 


301 


Cotkurnia,  139,  146. 
Craig  microscope,  5. 
Cricket,  gizzard  of,  281. 
Cristalella,  225,  229,  231. 
Crystals,  plant,  289. 

—  polariscope,  290. 
Cyclops,  241,  246,254. 
Cyclosis  in  Auacharis,  59. 

—  in  Closterium,  77. 

—  in  desmids,  68. 

—  in  Vallisneria,  60. 

Cynthia  Virginica,  crystal  prisms  in, 

290. 
Cyphoderia,  116,  129. 

—  ampulla,  129. 
Cypris,  246,  250. 

D. 

Dandelion,  287. 

Daphnia,  245,  247. 

Davies,  Thomas,  on  preparation  and 

mounting  of  microscopic  objects, 

46. 

Dendroccelum  lacieum,  183. 
Dcndromonas,  188,  140. 
Dero,  164,  188,  192. 
Desmidinm,  74,  77. 

—  Swartzii,  77. 
Desmids,  61,  64,72. 

—  key  to  genera  of,  66. 

—  to  preserve,  88. 

—  vacuoles  of,  68. 
Deutzia  scabra,  285. 
Diaphragm  of  microscope  stand,  22. 
Diaptonuts,  245,  246,  252. 
Diatoma,  93,  94. 

—  mdgare,  94. 
Diatoms,  61,  64,  72,  89,  92. 

—  as  food  for  microscopic  animals, 
92. 

Diatoms,  fossil,  91. 

—  key  to  genera  of,  93. 

—  literature,  92. 

—  movements,  66. 

—  structure,  90. 

—  surface  markings,  67,  89. 

—  to  study,  92. 
Didymoprium,  74,  76. 

— '  GremUii,  76. 
Difflugia,  112,  116,  123. 

—  acuminata,  125. 


Difflugia  corona,  125. 

—  globulosa,  125. 

—  pyriformix,  125. 
Dinobri/on,  138,144. 
Dinocharis,  208,  218. 
Diplodontus,  267,  269,  273. 
Dipper,  tin,  a  useful  collecting  tool, 

48. 
Dipping-tube,  34. 

—  to  make,  36. 

—  to  use,  35. 
Docidium,  75,  84. 

—  Baculum,  84. 

—  crenulatum,  84. 
Draparnaldia,  104,  108. 

—  glomerata,  108. 
Drawing  the  object,  41. 

—  camera  lucida  for,  42. 

—  reflector  for,  42. 
Draw-tube,  microscope,  11. 
Dry  object?,  to  examine,  26. 

to  mount,  33. 

Duckmeat  (Lemna),  48,  57. 


Eggs  of  Chironomm,  167. 

—  of  Eidomostraca,  240. 

—  of  insects,  281. 

—  of  Rotifers,  205. 

—  of  snails,  167. 

—  of  mapping-turtle,  205. 

—  of  Tubifex,  198. 

—  of  Turbdlaria,  181. 

—  of  water-mites,  167. 
Elytra,  279. 

Ernertoii's  "  Life  on  the  Sea-shore," 
x. 

—  "Structure  and  Habits  of  Spi- 
ders," x. 

Enchytrans,  188,  189. 

—  social^,  190. 

—  vermindaris,  190. 
Encyonema,  93,  96. 

—  paradoxa,  96. 
Entomostraca  and  Phyllopoda,  238. 

key  to  genera  of,  245. 

—  antennae,  239. 

—  beak,  239. 

—  effect  of  heat  on,  243. 

—  eggs  of,  240. 

—  eyes  of,  240. 


302 


INDEX. 


Entomostraca,  habitats  of,  241. 

—  heart,  240. 

—  Herrick,  C.  L.,  on,  242. 

—  literature,  259. 

—  reproduction,  240. 

—  usefulness  of,  242. 
.Epidermis  of  leaves,  284. 

Epistylis,  138,  142. 
Epit  hernia,  93,  97. 

—  turgida,  97. 
Equuetum  spores,  288. 
Eriyeron,  sphaeraphides  in,  289. 
Estkeria,  246,  256. 
Euastrum,  74,  83. 

—  ansatum,  84. 

—  crassum,  83. 
--  didelta,  84. 

Euglena,  139, 149. 
Euglyplia,  116,128. 

—  alveolata,  129. 

—  ciliata,  129. 

—  cristata,  129. 
Eunolia,  94,  97. 

—  tetraodon,  97. 
Euplotes,  140,  152. 
Evaporation    from   beneath    cover- 
glass,  37. 

Excelsior  microscope,  5. 
Eye-pieces,  construction  of,  11. 

—  different  powers  of,  12. 

—  eye-glass  of,  11. 

—  field-glass  of,  11. 

—  why  so  named,  10. 
Eyes  of  insects,  279. 

—  of  spiders,  280. 
Eylais,  267,  269. 

F. 

Feet  of  insects,  279. 
Field  of  view,  18. 
Fish,  scales  of,  282. 

—  small,  captured  by  Utricularia, 
55. 

Flagella  of  infusoria,  135. 
Fleabane,  289. 
Floscularia,  200,  207,  210. 
Flower-de-luce,  290. 
Focus,  objects  out  of,  20. 

—  of  compound  objective,  19. 

—  of  pocket-lens,  4,  5,  8. 
Foot  of  microscope  stand,  10. 


Fragelaria,  93,  95. 

—  capucina,  95. 
Fredericella,  229,  232. 

G. 

Gallic  acid  crystals,  291. 
Geranium,  seeds  of,  287. 

—  sphjeraphides  in,  289. 
Gizzard  of  insects,  281. 
Gladiolus,  crystal  prisms  in,  290. 
Glass,  thin  cover,  27,  28. 

—  thickness  of  the  three  kinds  of 
thin  cover,  29. 

Glass,  to  clean  thin  cover,  29. 
Gnats,  scales  from,  278. 
Golden-club,  289. 
Gomphonema,  93,  96. 

—  acuminata,  96. 

Gray's  "  How  Plants  Grow,"  x. 
Growing-slide,  a  simple,  38,  39. 

H. 

Hairs,  animal,  282. 

—  Anthrenus  larva,  283. 

—  plant,  286. 

—  stellate,  in  stems  of  water-lilv, 
50. 

Hairs,  stellate,  in  stems  of  Nuphar, 

51. 

Hawkweed,  290. 
Herrick,  C.  L.,  on  Eniomostraca,  242, 

259. 

Hervey's  "  Sea-mosses,"  x. 
Hibiscus,  sphffiraphides  in,  289. 
Hieratium,  crystal  prisms  in,  290. 
Himantidium, 93,  96. 

—  peciinalc,  96. 

Hitchcock's  "  Synopsis  of  the  Rhizo- 

pods,"  x.,  130. 
Hollyhock,  287. 
"  How  to  See  with  the  Microscope," 

by  J.  E.  Smith,  46. 
"How  to  Use  the  Microscope,"  by 

J.  Phinn,  46. 
"  How  to  Work  with  the  Microscope," 

by  Dr.  L.  S.  Bcale,  46. 
Ifyalotheca,  74,  76. 

—  dissilims,  76. 

Hyatt,  Prof.  Alphens,  on   Polyzoa, 

226,  237. 
Hydra,  60, 155. 


INDEX. 


303 


Hydra,  apparent  harsh  treatment  of, 

159. 
Hydra,  food  of,  157. 

—  fusca,  155, 158. 

—  'parasitic     infusoria     on,    160, 
Ifil. 

—  reproduction  of,  158. 

—  stings  of,  158. 

—  tentacles,  156. 

—  to  permanently  preserve,  161. 

—  translation  from  Trembley  on 
the,  159. 

Hydra  viridis,  155, 158. 
Hydrachna,  267,  269. 
Hydrachnidce,  266. 

I. 

Ickthydium  podura,  172. 
Impatiens  fnlva,  raphides  in,  289. 
Infusoria,  61,  131. 

—  colors  of,  135. 

—  free-swimming,  means  of  move- 
ment, 135. 

Infusoria,  illoricate,  134. 

—  in  infusion  of  hay,  134. 

—  key  to  genera  of,  138. 

—  loricate,  133,134. 

—  parasitic  on  Hi/dm,  160, 161. 

—  parasitic  on  Megalotrocha,  215. 

—  permanently  adherent,  134. 

—  preservation  of,  137. 

—  structure  of,  133. 

—  to  collect,  131. 

—  to  kill,  for  examination,  137. 

—  to  study,  136. 

—  water  colored  red  or  green  by, 
149. 

Insects,  eggs  of,  281. 

—  eyes,  279. 

—  feet,  279. 

—  from  the  cellar,  274. 

—  gizzard  of,  281. 

—  probosces,  280. 

—  to  examine,  281. 

Iodine  mixture  for  killing  infusoria, 
137. 

Iris  versicolor,  crystal  prisms  in, 
290. 

Iron,  pcrchloride,  for  killing  infu- 
soria, 137. 


J. 

Jordan's  "  Manual  of  the  Verte- 
brates," x. 

Journal  of  the  Academy  of  Natural 
Sciences  of  Philadelphia,  199,  236, 
237. 


Katydid,  gizzard  of,  282. 

Kerona  polyporum,  161. 

Key  to  desmids,  diatoms,  and  fresh- 
water algae,  71. 

Key  to  genera  of  fresh-water  algae, 
103. 

Key  to  genera  of  desmids,  74. 

—  to  genera  of  diatoms,  93. 

—  to  genera  of  Eutomostraca  and 
Phyllopoda,  245. 

Key  to  genera  of  Infusoria,  138. 

—  to  genera  of  Oligochaeta,  187. 

—  to  genera  of  Polyzoa,  228. 

—  to  genera  of  Rhizopods,  115. 

—  to  genera  of  Rotifers,  207. 

—  to  genera  of  Water-mites,  266. 

—  to  species  of  Chcetonotits,  171. 

—  to  species  of  Closterium,  78. 

—  to  species  of  Micraxlerias,  80. 

—  to  species  of  Stentor,  147. 
Keys,  analytical,  how  to  use,  70. 

—  to  Chironomnx,  C/uetonotns,  and 
classes  of  worms,  165. 

L. 

Ladnularia,  207,  208. 
JLeauminosce,  crystal  prisms  in,  290. 
Leidy,  Dr.  J.,  61, 193, 194,  199,  236, 

237,  277. 
Leidy,  Dr.  J.,  on  Rhizopods  of  North 

America,  130. 
Zemwa,48,  57,162. 

—  flower  of,  58. 

—  minor,  57. 

—  polyrrhiza,  57. 

—  raphides  in,  289. 

—  rootlets  of,  useful  to  the  micros- 
copist,  58. 

Lens,  Coddington,  7. 

—  pocket,  combination,  4. 
employment  for  the,  3,  234. 


304 


INDEX. 


Lens,  pocket,  simple,  2. 

—  —  simple,  with  long  focus  de- 
sirable, 4,  5. 

Lens,  pocket,  simple,  to  focus,  8. 

—  watchmaker's,  6. 

Lepisma    saccharina.    scales    from, 

269. 

Lichens,  274. 
Light,  importance  of  modifying  the, 

22. 

Lily,  the  white  water,  50. 
Limnetis,  246,  255. 
Limnms,  208,  214. 

—  annul  ata,  215. 


ZtmnocAara,  267,  270. 
Linden,  290. 

Lingual  ribbons  of  mollusks,  283. 
Lobelia  cardinalis,  seeds  of,  287. 
Lorica  of  infusoria,  133,  134. 
Loxodcs,  140,  154. 
Lumbriculus,  188,  191. 

M. 

Macrobiolm,  266,  267. 

—  Americanm,  268. 
Magazines,  American  Microscopical, 

46. 

Mallow,  common,  289. 
Malva  rotund/folia,  sphseraphides  in, 

289. 
"Manual  of  Microscopic  Mounting," 

Martin's,  46. 
"  Manual  of  the  Vertebrates,"  Jor- 

dan's, x. 
Maple,  290. 

Measuring  the  object,  43. 
Megalotrocha,  208,  215. 
Afc/teerto,  208,  212. 
Meridian,  93,  94. 

—  circulare,  94. 
Mermaid  weed,  52. 
Micrasterias,  74,  80. 

—  areuata,  82. 

—  dichotoma,  82. 

—  key  to  species  of,  80. 

—  KUduttii,  83. 

—  latictps,  83. 

—  oscilans,  83. 

—  radiosa,  81. 

—  truncata,  82. 


Micrometer,  stage,  43. 

—  to  ascertain  magnifying  power 
by  use  of,  44. 

Micrometer,  to  use,  44. 

Microscope,  books  relating  to  optical 

construction  of,  46. 
Microscope,  boy's  vertical,  18. 

—  compound,  2,  8. 

—  Craig,  5. 

—  Excelsior,  5. 

"  Microscope,  How  to  See  with  the," 

by  J.  E.  Smith,  46. 
"  Microscope,  How  to  Use  the,"  by 

J.  Phinn,  46. 
"  Microscope,  How    to   Work    with 

the,"  by  Dr.  L.  S.  Beale,"  46. 
Microscope,  parts  of  the,  1. 

—  simple,  1. 
action  of,  2. 

"Microscope,  the,  and   its   Revela- 
tions," by  Dr.  W.  B.  Carpenter,  46. 
Microscope,  to  adjust  for  use,  24. 

—  use   of,  not  injurious   to   eye- 
_sight,  23. 

Microscope,  vertical,  18. 
Microscopical  Society  of  London,  The 

Royal,  12. 
Mimulus  ringens.  crvstal  prisms  in, 

290. 

Mirror  of  microscope  stand,  23,  24. 
Mollusks,  lingual  ribbon  of,  283. 
Monkey  flower,  crystal  prisms  in,  290. 
Mosquito,  scales  from,  278. 
Moth,  common  clothes,  scales  from, 

278. 
Mounting,  microscopical,  25,  33. 

books  relating  to,  46. 

Myriophyllum,  48,  51. 


Nais,  164, 188, 198. 
Names  of  specimens,  the  desire  to 
know,  ix. 

Natural  history,  pleasure  of  study- 
ing, 277. 
Navicula,  94,  98. 

—  cuspidata,  98. 
Needles,  dissecting,  33. 
Nerium  Oleander,  stomata  of,  285. 

sphseraphides  in,  286. 

Note-book,  importance  of,  41. 


INDEX. 


305 


Note-book,  extract  from  a  boy's,  41. 
Nupliar,  51. 
Nymphcea  odorata,  50. 

0. 

Objectives,  American,  13, 14. 

—  care  of,  15. 

—  field  of,  276. 

—  French  triplet,  13. 

—  modern  American,  14. 

—  one-fifth  preferred  to  one-fourth, 
17. 

Objectives,  students'  series,  16. 

—  to  be  selected  by  the  beginner, 
16. 

Objectives,  to  focus,  19. 

—  why  so  named,  10. 
Objects,  opaque,  276. 

—  to  mount  microscopical,  25. 

—  to  prepare  microscope  for  ex- 
amination of,  24. 

Objects,  transparent,  276.       . 

—  worth  examining,  some  common, 
274. 

Ocnerodrilm,  187,  188,  195. 
Odontophore  of  mollusks,  283. 
(Enothera,  raphides  in,  289. 
Oleander,  spha:raphides  in,  286,  289. 

—  stomata  of,  285. 
Oliffochceta,  166, 184. 

—  beneath  decaying  bark,  189. 

—  blood  of,  186. 

—  bristles,  184, 185. 

—  fluid  in  body  cavity,  1SG. 

—  food,  187. 

—  key  to  genera  of,  187. 

—  mouth    and    alimentary   canal, 
186. 

—  podul  spines,  184, 185. 

—  reproduction,  1 87. 
Onion,  crystal  prisms  in,  290. 
Optical  construction  of  microscope, 

books  relating  to  the,  46. 
Orontium   aquaticum,  raphides   in, 

289. 

Oscillaria,  103, 105. 
Oxalis,  sphan-aphides  in,  289. 


Packard,  Dr.  A.  S.,  on  Branchipus, 
259. 


Packard,  Dr.  A.  S.,  on  Phyllopod 
Crustacea,  259. 

Palludicella,  229,  232. 

Paramcecium,  139, 152. 

Passion-flower,  287. 

Paste  eels,  184. 

Pedinatella,  224,  229. 
|    —  statoblasts,  230.      ' 

Pediastrvm,  71, 101. 
I    —  ffrannlatnm,  101. 
i  Penium,  75, 88. 
!    —  Brebissonii,  88. 

P/iacus,  139, 150. 
I    —  longicaudus,  150. 
j    —  plcuronectes,  150. 

Philodiim,  208,  220. 

Phyllopoda,  243,  245. 

—  branchial  plates  of,  243. 

—  eggs,  244. 

—  Entomostraca  and,  238. 

—  eyes,  244. 

—  literature,  259. 

—  to  examine,  244. 

—  western,  244. 

Pilea  pumila.  crystals  in  epidermis 

of,  290. 
Pinnularia,  94,  99. 

—  major,  99. 

—  viridis,  99. 
Pisidium,  253. 
Planaria  torva,  183. 

Plants,  common  aquatic,  to  identify, 

49. 
Plants,  common   aquatic,  useful  to 

the  microscopist,  47. 
Plants,    common    aquatic,   without 

English  names,  48. 
Platycola,  139, 145. 
Pleuros/fftna,  94,  97. 

—  angulatum,  98. 
Plumatella,  229,  231. 
Pocket-lens,  combination,  4. 

—  employment  for,  3,  274. 

—  simple,  2. 
Pollen,  286. 
Polyarthra,  208,  218. 
Polyzoa,  blood  of,  227. 

—  external  structure,  222. 

—  food,  227. 

—  fresh-water,  221. 

—  habitats,  222. 


306 


INDEX. 


Poljzoa,  habits,  222. 

—  key  to  genera  of,  228. 

—  jelly-like  loricse,  224. 

—  literature,  228. 

—  lophophore,  225. 

—  mouth,  225,  226. 

—  reproduction,  225. 

—  retraction  and  expansion,  227. 

—  stomach,  227. 

—  tentacles,  226. 

—  to  examine,  228. 

—  tubular  loricae  of,  226- 
Poppy,  seeds  of,  287. 
Porlulaca,  seeds  of,  287. 

—  sphaeraphides,  289. 
Potash  crystals,  chlorate  of,  291. 
Primrose,"289. 

Prisms,  long  crystal,  290. 

—  short  crystal,  290. 
Pristina,  164,  187,  188. 
Probosces  of  insects,  280. 
Proserpinaca,  52. 
Pseudopodia  of  Bhizopods,  111. 

—  pin-like  of  Vampyrella,  118. 
Plerodina,  208,  217. 
Pyrogallic  acid  crystals,  291. 

R. 
Eabbit's   foot   (Tn folium   arvense\ 

290. 

Ranunculus  aquatilis,  49. 
Raphides,  289. 

Reflector  for  drawing  the  object,  42, 
Rhizopods,  61,62,  111. 

—  books  relating  to  the,  x.,  130. 

—  favorite  haunts  of,  114. 

—  food  of  and  its  capture  by,  113. 

—  habitats,  114. 

—  illoricate,  112. 

—  key  to  genera  of,  115. 

—  loricate,  112. 

—  permanently  adherent,  1 30. 

—  pseudopodia,  111. 

—  structure,  111,  113. 

—  to  gather,  114. 
Riccia  fluitcms,  62. 
Richwced,  290. 
Rotifers,  200. 

—  eggs,  205. 

—  eyes,  200. 

—  foot,  202. 


Rotifers,  habitats,  206. 

—  key  to  genera  of,  207. 

—  literature,  207. 

—  loricse,  201. 

—  male,  206. 

—  mastax,  204,  206. 

—  moutli,  203. 

—  nibbling,  204. 

—  reproduction,  205. 

—  tail  of,  202. 

Rotifer  vidgaris,  202,  208,  216. 
Rubber  cement,  Brown's,  S3. 

S. 

S;ilt,  crystals  of,  291. 
Saponaria   officinalis,  sphaeraphides 

in,  289. 
Scales,  fish,  282. 

—  from  insects'  wings,  278. 

—  to  mount,  279. 
Scapholeberis,  246,  248. 
Scenedesmus,  71, 100. 

—  guadricauda,  100. 

Science  News  and  Boston  Journal  of 

Chemistry,  36. 
Screw,  the  Society,  12. 
Sea-mosses,  Hervey  on  the,  x. 
Seeds  of  wild  plants,  27,  287. 
Shellac  cement,  30. 
Sida,  246,  252. 
Slide,  a  simple  life,  38,  39. 
Slips  and  slides,  distinction  between, 

25. 

Slips,  proper  size  of,  27. 
Snails,  lingual  ribbon  of,  283. 
Spatterdock  (Nuphar),  51. 
Sphaeraphides,  286,  289. 
Sphcerozosma,  74,  76. 

—  pulchra,  76. 
Sphagnum,  60, 1 64. 
Spiders,  eyes  of,  280. 

—  feet  of,  279. 
Spiderwort  (Tradescantid),  289. 
Spiroffyra,103,  106. 

—  as  food  of  Difflugia,  124. 

—  as  food  of  Vampyrella,  119. 
Spirotcema,  75,  87. 

—  condensata,  87. 
Spores  of  Eqnisetum,  288. 
Spring-clips,  22. 
Squares,  thin  glass,  29. 


IXDEX. 


307 


Stage,  microscope,  21. 
Stand,  the  microscope,  9. 
Statoblasts  of  Cristatella,  231. 

—  of  Fredericella,  232. 

—  of  Pectinalella,  230. 

—  of  Urnatella,  236. 
Staurastrum,  75,  76,  85. 

—  fnrcigerum,  86. 

—  gracile,  86. 

—  macrocerum,  86. 

—  punctulatum,  86. 
Stauroneis,  94,  99. 

—  phcenocenteron,  99. 
Slentor,  139, 146. 

—  Barretti,  148. 

—  cceruleus,  148. 

—  igneus,  148. 

—  key  to  some  species  of,  147. 

—  niffer,  148. 

—  polymorphic,  148. 
Stephanoceros,  200,  207,  209. 
Stephana)*,  208,216. 
Strephuris,  188,  193. 
Stylonychia,  140, 153. 
Sugar  crystals,  275,  291. 
Surirella,  94,  98. 

—  splendida,  98. 
Sword-bearer,  219. 

T. 

Tardigrade,  268. 
Tartaric  acid  crystals,  291. 
Tetmemorus,  75,' 84. 

—  Hrebissonii,  84. 

—  granulahts,  84. 

7'Ae  Microscope  (magazine),  46. 
Thistles,  290. 

Touch-me-not  (Impaliens  fulva),  289 
Trachelocerca,  139,151. 
Tradescantia,  raphides  in,  289. 
Trembley  on  the  Hydra,  159. 
Trichodina  pedicidus,  1 60. 
TrifvUum,  crystal  prisms  in,  290. 
Trinema,  116",  127. 

—  enchelt/s,  127. 
Triplocerax,  75,  87. 

—  vertidllatum,  87. 
Tube,  glass-dipping,  34-36. 
Tublfex,  187,  188, 196.    . 

14* 


Turbellaria,  164, 166, 179. 

—  American  naturalists  on  181 

—  cilia  of,  180. 

—  eves,  180. 

—  food,  181. 

—  mouth,  180. 

—  propagation,  181. 
Turn-table,  31. 

U. 

Uiiio,  266. 
Urnalella,  229,  233. 

—  reproduction  of,  236. 
Utricles    of    Utricularia,    quadrifid 

processes  within  the,  55. 

Utricles  of  Utricularia,  structure  of 
54, 

Utricularia  vulgaris,  53. 
its  method  of  capturing  ani- 
mal food,  54. 

Uvella,  139, 150. 

V. 

Vaginicola,  139, 144. 
Vallimeria,  60. 

—  cyclosis  in,  60. 
Vampyrella,  115, 118. 

—  lateritia,  1 1 8. 
Vaucheria,  103,107. 
"inegar  eel,  184. 

Virginia  creeper  (Ampclopsis),  289 
Volvox,  72, 101. 

—  qlobator,  101. 
'^orticella,  135, 138,142. 


Tater  colored  by  Infusoria,  149. 

—  lost   by  evaporation  from   be- 
neath the  thin  cover,  to  supply, 
37. 

fater,  to  examine  objects  in,  27. 
rater»bear  (Macrobiotics),  266,  267. 
fater-lily,  white  (A'l/mpfuea),  50. 
fater-mitcs,  260,  263. 

—  cffica  of,  262. 

—  coxa  of,  264. 

—  eggs,  265. 


308 


IXDEX. 


Water-mites,  eyes,  261. 

—  food  of,  266. 

—  intestinal  opening,  264. 

—  legs  of,  265. 

—  literature,  273. 

—  markings  of,  261. 

—  mouth  of,  263. 

—  parasitic,  266. 

—  preserving  and  mounting,  273. 

—  propagation,  265. 

—  sexes,   external    differences    of 
the,  263. 


Water-mites,  tracheal  openings,  264. 

—  to  examine,  262. 

—  ventral  plates,  263. 

X. 

Xanthidinm,  75,  86. 

—  antilopceum,  87. 

—  armatum,  86. 


Zi/ynema,  103, 107. 
—  insiffne,  107. 


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WRITINGS  AND  SPEECHES  OF  SAMUEL  J.  'TILDES.  Edited 
by  JOHN  BIGELOW.  2  vols.,  8vo,  Cloth,  Gilt  Tops  and  Uncut  Edges, 

$6  00  per  set. 

GENERAL  DIX'S  MEMOIRS.  Memoirs  of  John  Adams  Dix.  Com- 
piled by  his  Son,  MORGAN  Dix.  With  Five  Steel-plate  Portraits. 
2  vols.,  Svo,  Cloth,  Gilt  Tops  and  Uncut  Edges,  $5  00. 

HUNT'S  MEMOIR  OF  MRS.  LIVINGSTON.  A  Memoir  of  Mrs. 
Edward  Livingston.  With  Letters  hitherto  Unpublished.  By  LOU- 
ISE LIVINGSTON  HUNT.  12mo,  Cloth,  $1  25. 

GEORGE  ELIOT'S  LIFE.  George  Eliot's  Life,  Related  in  her  Let- 
ters and  Journals.  Arranged  and  Edited  by  her  Husband,  J.  W. 
CKOSS.  Portraits  and  Illustrations.  In  Three  Volumes.  12mo, 
Cloth,  $3  75.  New  Edition,  with  Fresh  Matter.  (Uniform  with 
"Harper's  Library  Edition"  of  George  Eliot's  Works.) 

PEARS'S  FALL  OF  CONSTANTINOPLE.  The  Fall  of  Constan- 
tinople. Being  the  Story  of  the  Fourth  Crusade.  By  EDWIN 
PEARS,  LL.B.  8vo,  Cloth,  $2  50. 

KANKE'S  UNIVERSAL  HISTORY.  The  Oldest  Historical  Group 
of  Nations  and  the  Greeks.  By  LEOPOLD  VON  RANKE.  Edited  by 
G.  W.  PROTHERO,  Fellow  and  Tutor  of  King's  College,  Cambridge. 
Vol.  I.  Svo,  Cloth,  $2  50. 

LIFE  AND  TIMES  OF  THE  REV.  SYDNEY  SMITH.  A  Sketch 
of  the  Life  and  Times  of  the  Rev.  Sydney  Smith.  Based  on  Family 
Documents  and  the  Recollections  of  Personal  Friends.  By  STUART 
J.  REID.  With  Steel-plate  Portrait  and  Illustrations.  Svo,  Cloth, 
$3  00. 

STORMONTH'S  ENGLISH  DICTIONARY.  A  Dictionary  of  the 
English  Language,  Pronouncing,  Etymological,  and  Explanatory: 
embracing  Scientific  and  other  Terms,  Numerous  Familiar  Terms, 
and  a  Copious  Selection  of  Old  English  Words.  By  the  Rev.  JAMES 
STORMONTH.  The  Pronunciation  Revised  by  the  Rev.  P.  II.  PHELP, 
M.A.  Imperial  Svo,  Cloth,  $6  00;  Half  Roan,  $7  00;  Full  Sheep, 
$7  50.  (New  Edition.) 

PARTON'S  CARICATURE.  Caricature  and  Other  Comic  Art,  in 
All  Times  and  Many  Lands.  By  JAMES  PARTON.  203  Illustrations. 
Svo, 'Cloth,  Uncut  Edges  and  Gilt  Tops,  -$5  00;  Half  Calf,  $7  25. 

DU  CHAILLU'S  LAND  OF  THE  MIDNIGHT  SUN.  Summer 
and  Winter  Journeys  in  Sweden,  Norway,  Lapland,  and  Northern 
Finland.  By  PAUL  B.  Du  CIIAILLU.  Illustrated.  2  vols.,  Svo, 

Cloth,  $7  50  ;   Half  Calf,  $12  00. 


4  Valuable  Works  Jor  Public  and  Private  Libraries. 

LOSSING'S  CYCLOPAEDIA  OF  UNITED  STATES  HISTORY. 
From  the  Aboriginal  Period  to  187G.  By  B.  J.  LOSSING,  LL.D. 
Illustrated  by  2  Steel  Portraits  and  over  1000  Engravings.  2  vols., 
Royal  8vo,  Cloth,  $10  00;  Sheep,  $12  00;  Half  Morocco,  §15  00. 
(Sold  by  Subscription  only.) 

LOSSING'S  FIELD-BOOK  OF  THE  REVOLUTION.  Pictorial 
Field-Book  of  the  Revolution ;  or,  Illustrations  by  Pen  and  Pencil 
of  the  History,  Biography,  Scenery,  Relics,  and  Traditions  of  the 
War  for  Independence.  By  BENSON  J.  LOSSING.  2  vols.,  8vo, 
Cloth,  $H  00;  Sheep  or  Roan,  $15  00;  Half  Calf,  $18  00. 

LOSSING'S  FIELD-BOOK  OF  THE  WAR  OF  1812.  Pictorial 
Field-Book  of  the  War  of  1812  ;  or,  Illustrations  by  Pen  and  Pencil 
of  the  History,  Biography,  Scenery,  Relics,  and  Traditions  of  tho 
last  War  for  American  Independence.  By  BENSON  J.  LOSSING. 
With  several  hundred  Engravings.  1088  pages,  8vo,  Cloth,  $7  00 ; 
Sheep  or  Roan,  $8  50 ;  Half  Calf,  $10  00. 

MULLER'S  POLITICAL  HISTORY  OF  RECENT  TIMES  (1816- 
1875).  With  Special  Reference  to  Germany.  By  WILLIAM  MUL- 
LER.  Translated,  with  an  Appendix  covering  the  Period  from  1876 
to  1881,  by  the  Rev.  JOHN  P.  PETERS,  Ph.D.  12mo,  Cloth,  $3  00. 

STANLEY'S  THROUGH  THE  DARK  CONTINENT.  Through 
the  Dark  Continent ;  or,  The  Sources  of  the  Nile,  Around  the  Great 
Lakes  of  Equatorial  Africa,  and  Down  the  Livingstone  River  to  the 
Atlantic  Ocean.  149  Illustrations  and  10  Maps.  By  H.  M.  STAN- 
LET.  2  vols.,  8vo,  Cloth,  $10  00;  Sheep,  $12  00;  Half  Morocco, 
$15  00. 

STANLEY'S  CONGO.  The  Congo  and  the  Founding  of  its  Free 
State,  a  Story  of  Work  and  Exploration.  With  over  One  Hundred 
Full-page  and  smaller  Illustrations.  Two  Large  Maps,  and  several 
smaller  ones.  By  H.  M.  STANLEY.  2  vols.,  8vo,  Cloth,  $10  00; 
Sheep,  $12  00;  Half  Morocco,  $15  00. 

GREEN'S  ENGLISH  PEOPLE.  History  of  the  English  People. 
By  JOHN  RICHARD  GREEN,  M.A.  With  Maps.  4  vols.,  8vo,  Cloth, 
$10  00;  Sheep,  $12  00;  Half  Calf,  $19  00. 

GREEN'S  MAKING  OF  ENGLAND.  The  Making  of  England. 
By  JOHN  RICHARD  GREEN-.  With  Maps.  8vo,  Cloth,  $2  50 ;  Sheep, 
$3  00 ;  Half  Calf,  $3  75. 

GREEN'S  CONQUEST  OF  ENGLAND.  The  Conquest  of  England. 
By  JOHN  RICHARD  GREEN.  With  Maps.  8vo,  Cloth,  $2  50  ;  Sheep, 
$3  00  ;  Half  Calf,  $3  75. 


Valuable  TTorks  for  Public  and  Pi-irate  Libraries.  5 

ENGLISH    MEN   OF   LETTERS.      Edited   by  JOHN  MORLET. 

The  following  volumes  arc  now  ready.     Others  will  follow: 

JOHNSON.  By  L.  Stephen.  —  GIMOX.  By  J.  C.  Mori  son.— SCOTT.  By  R.  H.  Hut- 
ton.—  SHELLEY.  By  J.  A.  Symonds.—  GOLDSMITH.  By  W.  Black.— HUME.  By  Pro- 
fessor Huxley.— DKFOE.  By  W.  Minto.— BURNS.  By  Principal  Shairp.—  SPENSER. 
By  R.W.  Church.— THACKERAY.  By  A.  Trollope.—  BURKE.  By  J.  Morley.— MILTOX. 
By  M.  Pattison.— SOCTHEY.  By  E.  Dowden. — CHAUCER.  By  A.  W.  Ward. — BUXYAJJ. 
By  J.  A.  Fronde.— COWPER.  By  G.  Smith. — POPE.  By  L.  Stephen. — BYROX.  By 
J.  Nichols. — LOCKE.  By  T.  Fowler. — WORDSWORTH.  By  F.  W.  H.  Myers. — HAW- 
THOKXE.  By  Henry  James,  Jr. — DRYDEX.  By  G.  Saintsbury. — LAXDOR.  By  S.  Col- 
vin. — DE  QCISCEY.  By  D.  Masson. — LAMB.  By  A.  Ainger. — BEXTLEY.  By  R.  C. 
Jebb. — DICKENS.  By  A.  W.  Ward. — GRAY.  ByE.W.  Gosse. — SWIFT.  By  L.Stephen. 
— STERXE.  By  H.  D.  Traill. — MACAULAY.  By  J.  C.  Morison. — FIELDING.  By  A.  Dob- 
son. — SHERIDAX.  By  Mrs.  Oliphant. — ADDISOX.  By  W.  J.  Courthope. — BACOX.  By 
R.  W.  Church. — COLERIDGE.  By  H.  D.  Traill. — SIR  PHILIP  SIDNEY.  By  J.  A.  Sy- 
monds. 12mo,  Cloth,  75  cents  per  volume. 

EEBER'S  HISTORY  OF  ANCIENT  ART.  History  of  Ancient 
Art.  By  Dr.  FRANZ  VON  REBER.  Revised  by  the  Author.  Trans- 
lated and  Augmented  by  Joseph  Thacher  Clarke.  With  310  Illus- 
trations and  a  Glossary  of  Technical  Terms.  8vo,  Cloth,  $3  50. 

REBER'S  MEDIAEVAL  ART.  History  of  Mediaeval  Art.  By  Dr. 
FKANZ  VON  REBER.  Translated  and  Augmented  by  Joseph  Thacher 
Clarke.  With  422  Illustrations,  and  a  Glossary  of  Technical  Terms. 

8vo,  Cloth,  $5  00. 

NEWCOMB'S  ASTRONOMY.  Popular  Astronomy.  By  SIMON 
NEWCOMB,  LL.D.  With  112  Engravings,  and  5  Maps  of  the  Stars. 
8vo,  Cloth,  $2  50;  School  Edition,  12mo,  Cloth,  $1  30. 

VAN-LENNEP'S  BIBLE  LANDS.  Bible  Lands :  their  Modern  Cus- 
toms and  Manners  Illustrative  of  Scripture.  By  HKNRY  J.  VAN- 
LENNEP,  D.D.  350  Engravings  and  2  Colored  Maps.  8vo,  Cloth, 
$5  00 ;  Sheep,  $6  00 ;  Half  Morocco,  $8  00. 

CESNOLA'S  CYPRUS.  Cyprus:  its  Ancient  Cities,  Tombs,  and 
Temples.  A  Narrative  of  Researches  and  Excavations  during  Ten 
Years'  Residence  in  that  Island.  By  L.  P.  DI  CRSNOLA.  With 
Portrait,  Maps,  and  400  Illustrations.  8vo,  Cloth,  Extra,  Uncut 
Edges  and  Gilt  Tops,  $7  50. 

TENNYSON'S  COMPLETE  POEMS.  The  Complete  Poetical  Works 
of  Alfred,  Lord  Tennyson.  With  an  Introductory  Sketch  by  Anne 
Thackeray  Ritchie.  With  Portraits  and  Illustrations.  8vo,  Extra 
Cloth,  Bevelled,  Gilt  Edges,  $2  50. 

SHORT'S  NORTH  AMERICANS  OF  ANTIQUITY.  The  North 
Americans  of  Antiquity.  Their  Origin,  Migrations,  and  Type  of 
Civilization  Considered.  By  JOHN  T.  SHOUT.  Illustrated.  8vo, 
Cloth,  $3  00. 


6  Valuable  Works  for  Public  and  Private  Libraries. 

GROTE'S  HISTORY  OF  GREECE.  12  vols.,  12mo,  Cloth,  $18  00; 
Sheep,  $22  80 ;  Half  Calf,  $39  00. 

FLAMMARION'S  ATMOSPHERE.  Translated  from  the  French 
of  CAMILLE  FLAMMARION.  With  10  Chromo-  Lithographs  and  86 
Wood-cuts.  8vo,  Cloth,  $6  00  ;  Half  Calf,  $8  25. 

BAKER'S  ISMAILIA  :  a  Narrative  of  the  Expedition  to  Central  Af- 
rica for  the  Suppression  of  the  Slave  -  trade,  organized  by  Ismail, 
Khedive  of  Egypt.  By  Sir  SAMUEL  W.  BAKER.  With  Maps,  Por- 
traits, and  Illustrations.  8vo,  Cloth,  $5  00;  Half  Calf,  $7  25. 

LIVINGSTONE'S  ZAMBESI.  Narrative  of  an  Expedition  to  the 
Zambesi  and  its  Tributaries,  and  of  the  Discovery  of  the  Lakes 
Shirwa  and  Nyassa,  1858  to  1864.  By  DAVID  an4d  CHARLES  LIV- 
INGSTONE. Illustrated.  8vo,  Cloth,  $5  00;  Sheep,  $5  50;  Half 
Calf,  $7  25. 

LIVINGSTONE'S  LAST  JOURNALS.  The  Last  Journals  of  Da- 
vid Livingstone,  in  Central  Africa,  from  1865  to  his  Death.  Con- 
tinued by  a  Narrative  of  his  Last  Moments,  obtained  from  his 
Faithful  Servants  Chuma  and  Susi.  By  HORACE  WALLER.  With 
Portrait,  Maps,  and  Illustrations.  8vo,  Cloth,  $5  00;  Sheep,  $6  00. 

BLAIKIE'S  LIFE  OF  DAVID  LIVINGSTONE.  Memoir  of  his 
Personal  Life,  from  his  Unpublished  Journals  and  Correspondence. 
By  W.  G.  BLAIKIE,  D.D.  With  Portrait  and  Map.  8vo,  Cloth, 
$2  25. 

"  THE  FRIENDLY  EDITION  "  of  Shakespeare's  Works.  Edited  by 
W.  J.  ROLFE.  In  20  vols.  Illustrated.  16mo,  Gilt  Tops  and  Un- 
cut Edges,  Sheets,  $27  00  ;  Cloth,  $30  00  ;  Half  Calf,  $60  per  Set. 

GIESELER'S  ECCLESIASTICAL  HISTORY..  A  Text -Book  of 
Church  History.  By  Dr.  JOHN  C.  L.  GIESELER.  Translated  from 
the  Fourth  Revised  German  Edition.  Revised  and  Edited  by  Rev. 
HENRY  B.  SMITH,  D.D.  Vols.  I.,  II.,  III.,  and  IV:,  Svo/Cloth, 
$2  25  each;  Vol.  V.,  8vo,  Cloth,  $3  00.  Complete  Sets',  5  vols., 
Sheep,  $14  50;  Half  Calf, -$23  25. 

CURTIS'S  LIFE  OF  BUCHANAN.  Life  of  James  Buchanan,  Fif- 
teenth President  of  the  United 'States.  By  GEOUGK  TICKNOR  CUR- 
TIS. With  Two  Steel  Plate  Portraits.  2  vols.,  8vo,  Cloth,  Uncut 
Edges  and  Gilt  Tops,  $6  00. 

COLERIDGE'S  WORKS.  The  Complete  Works  of  Samuel  Taylor 
Coleridge.  Writh  an  Introductory  Essay  upon  his  Philosophical  and 
Theological  Opinions.  ..Edited  by  Professor  W.  G.  T.  SHEDD.  With 
Steel  Portrait,  ahd  an  Index.  7  vols.,  12mo,  Cloth,  $2  00  per  vol- 
ume ;  $12  00  per  set;  -Half  Calf,  $24  25. 


Valuable  Works  for  Public  and  Private  Libraries.  7 

GRIFFIS'S  JAPAN.  The  Mikado's  Empire:  Book  I.  History  of 
Japan,  from  660  B.C.  to  1872  A.D.  Book  II.  Personal  Experiences, 
Observations,  and  Studies  in  Japan,  from  1870  to  1874.  With  Two 
Supplementary  Chapters:  Japan  in  1883,  and  Japan  m  1880.  By 
W.  E.  GUIFFJS.  Copiously  Illustrated.  8vo,  Cloth,  $4  00;  Half  Calf, 
$6  25. 

SMILES'S  HISTORY  OF  THE  HUGUENOTS.  The  Huguenots: 
their  Settlements,  Churches,  and  Industries  in  England  and  Ireland. 
By  SAMUEL  SMILES.  With  an  Appendix  relating  to  the  Huguenots 
in  America.  Crown,  8vo,  Cloth,  $2  00. 

SMILES'S  HUGUENOTS  AFTER  THE  REVOCATION.  The  Hu- 
guenots in  France  after  the  Revocation  of  the  Edict  of  Nantes;  with 
a  Visit  to  the  Country  of  the  Vaudois.  By  SAMUEL  SMILES.  Crown 
8vo,  Cloth,  $2  00. 

SMILES'S  LIFE  OF  THE  STEPHENSONS.  The  Life  of  George 
Stephenson,  and  of  his  Son,  Robert  Stephenson  ;  comprising,  also,  a 
History  of  the  Invention  and  Introduction  of  the  Railway  Locomo- 
tive. By  SAMUEL  SMILES.  Illustrated.  8vo,  Cloth,  $3  00. 

THE  POETS  AND  POETRY  OF  SCOTLAND :  From  the  Earliest 
to  the  Present  Time.  Comprising  Characteristic  Selections  from 
the  Works  of  the  more  Noteworthy  Scottish  Poets,  with  Biographi- 
cal and  Critical  Notices.  By  JAMES  GRANT  WILSON.  With  Por- 
traits on  Steel.  2  vols.,  Svo/Cloth,  $10  00  ;  Gilt  Edges,  $11  00. 

SCHLIEMANN'S  ILIOS.  liios,  the  City  and  Country  of  the  Trojans. 
A  Narrative  of  the  Most  Recent  Discoveries  and  Researches  made 
on  the  Plain  of  Troy.  By  Dr.  HENRY  SCHLIEMANN.  Maps,  Plans, 
and  Illustrations.  Imperial  Svo,  Illuminated  Cloth,  $12  00;  Half 
Morocco,  $15  00. 

SCHLIEMANN'S  TROJA.  Troja.  Results  of  the  Latest  Researches 
and  Discoveries  on  the  Site  of  Homer's  Troy,  and  in  the  Heroic  Tu- 
muli and  other  Sites,  made  in  the  Year  1882,  and  a  Narrative  of  a 
Journey  in  the  Troad  in  1881.  By  Dr.  HENRY  SCHLIEMAXW.  Pref- 
ace by  Professor  A.  H.  Sayce.  With  Wood-cuts,  Maps,  and  Plans. 
Svo,  Cloth,  $7  50;  Half  Morocco,  $10  00. 

SCHWEINFURTH'S  HEART  OF  AFRICA.  Three  Years'  Travels 
and  Adventures  in  the  Unexplored  Regions  of  the  Centre  of  Africa— 
from  1868  to  1871.  By  GEORG  SCUWEINFURTH.  Translated  by 
ELLEN  E.  FREWER.  Illustrated.  2  vols.,  Svo,  Cloth,  $8  00. 

NORTON'S  STUDIES  OF  CHURCH-BUILDING.  Historical  Stud- 
ies of  Church-Building  in  the  Middle  Ages.  Venice,  Siena,  Flor- 
ence. Bv  CHARLES  ELIOT  NORTON.  Svo,  Cloth,  $3  00. 


8  Valuable  Works  for  Public  and  Private  Libraries. 

THE  VOYAGE  OF  THE  "  CHALLENGER."  The  Atlantic  :  an 
Account  of  the  General  Results  of  the  Voyage  during  1873,  and  the 
Early  Part  of  1876.  By  Sir  WYVILLE  THOMSON,  K.C.B.,  F.R.S. 

Illustrated.     2  vols.,  8vo,  Cloth,  $12  00. 

THE  STUDENT'S  SERIES.  Maps  and  Illustrations.  12mo,  Cloth  : 
FRANCE. — GIBBON. — GREECE. — ROME  (hy  LIDDELL). — OLD  TES- 
TAMENT HISTORY. — NEW  TESTAMENT  HISTORY. — STRICKLAND'S 
QUEENS  OF  ENGLAND. — ANCIENT  HISTORY  OF  THE  EAST. — HAL- 
LAM'S  MIDDLE  AGES.  —  HALLAM'S  CONSTITUTIONAL  HISTORY  OF 
ENGLAND. —  LYELL'S  ELEMENTS  OF  GEOLOGY. —  MERIVALE'S  GEN- 
ERAL HISTORY  OF  ROME.  —  Cox's  GENERAL  HISTORY  OF  GREECE. 
— CLASSICAL  DICTIONARY. — SKEAT'S  ETYMOLOGICAL  DICTIONARY. — 
RAAVLINSON'S  ANCIENT  HISTORY.  $1  25  per  volume. 

LEWIS'S  HISTORY  OF  GERMANY. — ECCLESIASTICAL  HISTORY,  Two 
Vols. — HUME'S  ENGLAND. — MODERN  EUROPE.     $1  50  per  volume. 
WESTCOTT  AND  HORT'S  GREEK  TESTAMENT,  $1  00. 

THOMSON'S  SOUTHERN  PALESTINE  AND  JERUSALEM. 
Southern  Palestine  and  Jerusalem.  Biblical  Illustrations  drawn 
from  the  Manners  and  Customs,  the  Scenes  and  Scenery,  of  the 
Holy  Land.  By  W.  M.  THOMSON,  D.D.  140  Illustrations  and 
Maps.  Square  8vo,  Cloth,  $6  00 ;  Sheep,  $7  00 ;  Half  Morocco, 
$8  50;  Full  Morocco,  Gilt  Edges,  $10  00. 

THOMSON'S  CENTRAL  PALESTINE  AND  PHOENICIA.  Cen- 
tral  Palestine  and  Phoenicia.  Biblical  Illustrations  drawn  from  the 
Manners  and  Customs,  the  Scenes  and  Scenery,  of  the  Holy  Land. 
By  W.  M.  THOMSON,  D.D.  130  Illustrations  and  Maps.  Square  8vo, 
Cloth,  $6  00;  Sheep,  $7  00;  Half  Morocco,  $8  50;  Full  Morocco, 
$10  00. 

THOMSON'S  LEBANON,  DAMASCUS,  AND  BEYOND  JORDAN. 

Lebanon,  Damascus,  and  beyond  Jordan.  Biblical  Illustrations  drawn 
from  the  Manners  and  Customs,  the  Scenes  and  Scenery,  of  the  Holy 
Land.  By  W.  M.  THOMSON,  D.D.  147  Illustrations  and  Maps. 
Square  8vo,  Cloth,  $6  00;  Sheep,  $7  00;  Half  Morocco,  $8  50; 
Full  Morocco,  $10  00. 

Popular  Edition  of  the  above  three  volumes,  8vo,  Ornamental  Cloth, 
$9  00  per  set. 

CYCLOPAEDIA  OF  BRITISH  AND  AMERICAN  POETRY.  Ed- 
ited by  EPES  SARGENT.  Royal  8vo,  Illuminated  Cloth,  Colored 
Edges,  $4  50;  Half  Leather,  8*5  00. 

EATON'S  CIVIL  SERVICE.  Civil  Service  in  Great  Britain.  A 
History  of  Abuses  and  Reforms,  and  their  bearing  upon  American 
Politics.  By  DORMAN  B.  EATON.  8vo,  Cloth,  $2  50. 


Valuable  Works  for  PuUic  and  Private  Libraries.  9 

CAMERON'S  ACROSS  AFRICA.  Across  Africa.  By  VEHNEY  Lov- 
ETT  CAMERON.  Map  and  Illustrations.  8vo,  Cloth,  $5  00. 

CARLYLE'S  FREDERICK  THE  GREAT.  History  of  Friedrich 
II.,  called  Frederick  the  Great.  By  THOMAS  CARLTLE.  Portraits, 
Maps,  Plans,  &c.  6  vols.,  12mo,  Cloth,  $7  50  ;  Sheep,  $9  90 ;  Half 
Calf,  $18  00. 

CARLYLE'S  FRENCH  REVOLUTION.  The  French  Revolution : 
a  History.  By  THOMAS  CARLYLE.  2  vols.,  12mo,  Cloth,  $2  50; 

Sheep,  $2  90  ;  Half  Calf,  $4  25. 

CARLYLE'S  OLIVER  CROMWELL.  Oliver  Cromwell's  Letters 
and  Speeches,  including  the  Supplement  to  the  First  Edition.  With 
Elucidations.  By  THOMAS  CARLYLE.  2  vols.,  I2mo,  Cloth,  $2  50  ; 
Sheep,  $2  90 ;  Half  Calf,  $4  25. 

PAST  AND  PRESENT,  CHARTISM,  AND  SARTOR  RESARTUS. 
By  THOMAS  CARLYLE.  12mo,  Cloth,  $1  25. 

EARLY  KINGS  OF  NORWAY,  AND  THE  PORTRAITS  OF  JOHN 
KNOX.  By  THOMAS  CARLYLE.  12mo,  Cloth,  $1  25. 

REMINISCENCES  BY  THOMAS  CARLYLE.  Edited  by  J.  A. 
FROUDE.  12mo,  Cloth,  with  Copious  Index,  and  with  Thirteen  Por- 
traits, 50  cents. 

FROUDE'S  LIFE  OF  THOMAS  CARLYLE.  PART  I.  A  History 
of  the  First  Forty  Years  of  Carlyle's  Life  (1795-1835).  By  JAMES 
ANTHONY  FROUDE,  M.A.  With  Portraits  and  Illustrations.  2  vol- 
umes in  one,  12mo,  Cloth,  $1  00. 

PART  II.  A  History  of  Carlyle's  Life  in  London  (1834-1881).  By 
JAMES  ANTHONY  FROUDE.  Illustrated.  2  volumes  in  one.  12mo, 
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M'CARTHY'S  HISTORY  OF  ENGLAND.  A  History  of  Our  Own 
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ABBOTT'S  HISTORY  OF  THE  FRENCH  REVOLUTION.  The 
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ABBOTT'S  NAPOLEON.  The  History  of  Napoleon  Bonaparte. 
By  JOHN  S.  C.  ABBOTT.  Maps,  Illustrations,  and  Portraits.  2 
vols.,  8vo,  Cloth,  $10  00;  Sheep,  $11  00;  Half  Calf,  $11  50. 

ABBOTT'S  NAPOLEON  AT  ST.  HELENA.  Napoleon  at  St. 
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the  Years  of  his  Captivity.  Collected  from  the  Memorials  of  Las 
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ABBOTT'S  FREDERICK  THE  GREAT.  The  History  of  Frederick 
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Illustrated.  8vo,  Cloth,  $5  00;  Half  Calf,  $7  25. 

TROLLOPE'S  AUTOBIOGRAPHY.  An  Autobiography.  By  AN- 
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TROLLOPE'S  CICERO.  Life  of  Cicero.  By  ANTHONY  TROLLOPE. 
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FOLK-LORE  OF  SHAKESPEARE.  By  the  Rev.  T.  F.  THISELTON 
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WATSON'S  MARCUS  AURELIUS  ANTONINUS.  Marcus  Anreli- 
us  Antoninus.  By  PAUL  BARRON  WATSON.  Crown  8vo,  Cloth, 
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THOMSON'S  THE  GREAT  ARGUMENT.  The  Great  Argument ; 
or,  Jesus  Christ  in  the  Old  Testament.  By  W.  H.  THOMSON,  M.A., 
M.D.  Crown  8vo,  Cloth,  $2  00. 

HUDSON'S  HISTORY  OF  JOURNALISM.  Journalism  in  the  United 
States,  from  1690  to  1872.  By  FREDERIC  HUDSON.  8vo,  Cloth, 
$5  00;  Half  Calf,  $7  25. 

SHELDON'S  HISTORY  OF  CHRISTIAN  DOCTRINE.  History 
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tory, in  Boston  University.  2  vols.,  8vo,  Clorb,  $3  50  per  set. 

DEXTER'S  CONGREGATIONALISM.  The  Congregationalism  of 
the  Last  Three  Hundred  Years,  as  Seen  in  its  Literature :  with 
Special  -Reference  to  certain  Recondite,  Neglected,  or  Disputed 
Passages.  With  a  Bibliographical  Appendix.  By  H.  M.  DEXTER. 
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SYMONDS'S  SKETCHES  AND  STUDIES  IN  SOUTHERN  EU- 
ROPE. By  JOHN  ADDINGTON  SYMONDS.  2  vols.,  Square  16mo 
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SYMONDS'S  GREEK  POETS.  Studies  of  the  Greek  Poets.  By 
JOHN  ADDINGTON  SYMONDS.  2  vols.,  Square  IGmo,  Cloth  $3  50- 
Half  Calf,  $7  00. 

MAHAFFY'S  GREEK  LITERATURE.  A  History  of  Classical 
Greek  Literature.  By  J.  P.  MAHAFFY.  2  vols.,  12mo,  Cloth, 

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DU  CHAILLU'S  ASHANGO  LAND.  A  Journey  to  Ashango  Land, 
and  Further  Penetration  into  Equatorial  Africa.  By  PAUL  B. 
Do  CHAILLU.  Illustrated.  8vo,  Cloth,  $5  00 ;  Half  Calf,  $7  25. 

SIMCOX'S  LATIN  LITERATURE.  A  History  of  Latin  Literature, 
from  Ennius  to  Boethins.  By  GEORGE  AUGUSTUS  SIMCOX,  M.A.  2 
vols.,  12mo,  Cloth,  $4  00. 

BARTLETT'S  FROM  EGYPT  TO  PALESTINE.  Through  Sinai, 
the  Wilderness,  and  the  South  Country.  Observations  of  a  Journey 
made  with  Special  Reference  to  the  History  of  the  Israelites.  By 
S.  C.  BARTLETT,  D.D.  Maps  and  Illustrations.  8vo,  Cloth,  $3  50. 

KINGLAKE'S  CRIMEAN  WAR.  The  Invasion  of  the  Crimea:  its 
Origin,  and  an  Account  of  its  Progress  down  to  the  Death  of  Lord 
Raglan.  By  ALEXANDER  WILLIAM  KINGLAKE.  With  Maps  and 
Plans.  Four  Volumes  now  ready.  12rno,  Cloth,  $2  00  per  vol. 

NEWCOMB'S  POLITICAL  ECONOMY.  Principles  of  Political 
Economy.  By  SIMON  NEWCOMB,  LL.D.,  Professor  of  Mathematics, 
U.  S.  Navy,  Professor  in  the  Johns  Hopkins  University,  pp.  xvi., 
548.  8vo,  Cloth,  $2  50. 

SIIAKSPEARE.  The  Dramatic  Works  of  Shakspeare.  With  Notes. 
Engravings.  6  vols.,  12mo,  Cloth,  .$9  00.  2  vols.,  8vo,  Cloth,  $4  00 ; 
Sheep,  $5  00.  In  one  vol.,  8vo,  Sheep,  $4  00. 

GENERAL  BEAUREGARD'S  MILITARY  OPERATIONS.  The 
Military  Operations  of  General  Beauregard  in  the  War  Between  the 
States,  1861  to  1865;  including  a  brief  Personal  Sketch,  and  a  Nar- 
rative of  his  Services  in  the  War  with  Mexico,  1846  to  1848.  By 
ALFRED  ROMAN,  formerly  Aide-de-Camp  on  the  Staff  of  General 
Beauregard.  With  Portraits,  &c.  2  vols.,  8vo,  Cloth,  $7  00 ;  Sheep, 
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NORDHOFF'S  COMMUNISTIC  SOCIETIES  OF  THE  UNITED 
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Personal  Visit  and  Observation  ;  including  Detailed  Accounts  of  the 
Economists,  Zoarites,  Shakers,  the  Amana,  Oncida,  Bethel,  Aurora, 
Icarian,  and  other  existing  Societies.  By  CHARLES  NORDHOFF.  Il- 
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BOSWELL'S  JOHNSON.  The  Life  of  Samuel  Johnson,  LL.D.,  in- 
cluding a  Journal  of  a  Tour  to  the  Hebrides.  By  JAMES  BOSWELL. 
Edited  by  J.  W.  CROKER,  LL.D.,  F.E.S.  With  a  Portrait  of  Bos- 
well.  2  vols.,  8vo,  Cloth,  $4  00;  Sheep,  $5  00. 

BROUGHAM'S  AUTOBIOGRAPHY.  Life  and  Times  of  Henry, 
Lord  Brougham.  Written  by  Himself.  3  vols.,  12mo,  Cloth,  $G  00. 

BOURNE'S  LOCKE.  The  Life  of  John  Locke.  By  II.  R.  Fox 
BOURNE.  2  vols.,  8vo,  Cloth,  $5  00. 

EARTH'S  NORTH  AND  CENTRAL  AFRICA.  Travels  and  Di«- 
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the  Years  1849-1855.  By  HENRY  BAKTII,  Ph.D.,  D.C.L.  Illus- 
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BULWER'S  LIFE  AND  LETTERS.  Life,  Letters,  and  Literary 
Remains  of  Edward  Bulwer,  Lord  Lytton.  By  his  Son,  the  EARL 
OF  LYTTON  ("Owen  Meredith").  Volume  I.  Illustrated.  12mo, 
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BULWER'S  HORACE.  The  Odes  and  Epodes  of  Horace.  A  Met- 
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taries. With  Latin  Text  from  the  Editions  of  Orelli,  Macleane,  and 
Yonge.  12mo,  Cloth,  $1  75. 

BULWER'S  MISCELLANEOUS  WORKS.  Miscellaneous  Prose 
Works  of  Edward  Bulwer,  Lord  Lytton.  In  Two  Volumes.  12mo, 
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PERRY'S  HISTORY  OF  THE  CHURCH  OF  ENGLAND.  A 
History  of  the  English  Church,  from  the  Accession  of  Henry  VIII. 
to  the  Silencing  of  Convocation.  By  G.  G.  PERRY,  M.A.  With  a 
Sketch  of  the  History  of  the  Protestant  Episcopal  Church  in  the 
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FORSTER'S  LIFE  OF  DEAN  SWIFT.  The  Early  Life  of  Jona- 
than Swift  (1G67-1711).  By  JOHN  FORSTEK.  With  Portrait.  8vo, 

Cloth,  Uncut  Edges  and  Gilt  Tops,  $2  50. 


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